However, one day, when Michael was ten, Byron went out on an expedition with Dr. Faker and an explorer named Kazuma Tsukumo, only to be be betrayed by Faker and sacrificed alongside Kazuma to open a portal to the Barian World. Because Byron failed to return, Michael's mother was long dead, and Christopher wasn't considered old enough to be a valid guardian at the time, both a young Michael and Thomas were left to an orphanage while Christopher continued to work for Dr. Faker to investigate what happened to Byron. Both Michael and Thomas remained in the orphanage for some time with only each other for family until, one day, Byron abruptly returned from the Barian World he had been trapped in, his form warped into a more childlike state. Upon his return, Christopher, now aware of what Dr. Faker had done, left Dr. Faker's facility to side with his father, briefly returning to Britain to get Michael and Thomas out of the orphanage in the process.

Despite being reunited, things weren't the same after that, as Byron had been granted power by the Barians in exchange for gathering the Number cards to destroy the Astral World. Now obsessed with revenge against Dr. Faker, he renamed himself Tron and likewise stripped his sons of their birth names, giving them Roman Numerals as names instead; Christopher became V, Thomas became IV, and Michael became III. Roughly around the same time, III, IV, and V were given special crests that would allow them to freely use Number cards without being controlled by them and the ability to warp from point to point, but at the cost of removing their souls if they ever lost a duel while using powerful Numbers.

The family quickly fell into dysfunction as the three brothers began being used as pawns in Tron's revenge scheme, often to hunt and collect Numbers or to perform specific tasks for Tron. It's at this point that III began to be affected by the increasingly dysfunctional state of his family, as he began to effectively enable IV's sadistic 'Special Fanservice Duels' (read: IV beats up unfortunate duelists in massively lopsided duels in an overkill way) by watching them happen and doing nothing to stop them from happening. Likewise, III also began doing whatever tasks Tron asked him to do without question, having long given up on fighting against his now unreasonable father. Still, he maintained his deep desire to see his family go back to normal, even if he had no way to act on it beyond defusing arguments between IV and V.

Eventually, when III was fifteen, Mr. Heartland announced the World Duel Carnival tournament that would be happening in Heartland City. The whole family signed up as participants, and when the first day of the tournament rolled around, III used that first day to collect all the Heart Pieces he would need to advance to the second phase. This turned out to be wise, as at the start of the second day III was tasked with delivering the Number card 'Number 32: Shark Drake' to a duelist named Ryoga Kamishiro. III accompanied IV out to accomplish his task, and after watching yet another of IV's 'Fanservice Duels' happen, Ryoga himself showed up to confront IV. III quickly stepped in to intercept Ryoga, casually telling his brother there was no need for him to duel Ryoga and that Tron's orders were absolute before forcing Ryoga into dueling him instead via use of a Duel Anchor to prevent Ryoga from leaving.

Once the duel began, III set up a scenario in which he summoned Shark Drake himself, but made it easy for Ryoga to take the monster onto his own side of the field. Ryoga quickly took the bait, stealing control of Shark Drake from III just as he wanted. It's at this point that Shark Drake should have possessed Ryoga, who had no means of resisting Number control-

-but Ryoga resisted being manipulated through willpower alone, much to III's surprise. Still, III pressed on with the duel, continuing to put in his best effort despite having been told by Tron that he could just throw the duel after delivering Shark Drake. III ultimately lost anyways, but took the loss in stride and revealed that he had already collected his required Heart Pieces for the tournament before returning home. On arriving back home and confirming that he'd delivered the card, III mentioned how Ryoga had resisted being controlled, only for Tron to reveal that he hadn't; Shark Drake could still potentially take control if the anger in Ryoga's heart grew.

Later that day, the next phase of Tron's revenge scheme was activated as V was sent to kidnap Dr. Faker's younger son Haruto. On being brought to the Arclight home, Tron performed a ritual to steal Haruto's power; this ritual caused Haruto pain and was uncomfortable for III to have to watch. However, it wasn't long before Haruto's older brother Kaito arrived alongside a boy named Yuma Tsukumo (and an alien being named Astral, though only Yuma could actually see Astral), and III and IV were sent to stop them from interrupting the ritual.

III and IV quickly forced Kaito and Yuma into a Tag Duel, and, working together, managed to successfully entrap Kaito's signature Galaxy Eyes Photon Dragon and began to wear at Kaito's LP. (Though their cooperation hit a brief snag when III objected to IV tormenting Kaito with footage of Haruto being forced through the ritual on the grounds of it being especially cruel.) III and IV likely would have won, if it weren't for both Yuma constantly trying to support and protect Kaito and Kaito himself abruptly getting the ability to XYZ summon Neo Galaxy Eyes Photon Dragon, which he used to turn the tides and beat III and IV.

This duel had major effects on III in particular; it caused him to become curious about Yuma's determination and ability to fight without hatred, and he briefly caught a glimpse of Astral when his crest activated to stop Astral from taking his Number card (Number 33: Chronomaly Machu Mech) from him. IV and III retreated while V briefly showed up and returned an unconscious Haruto to Kaito.

The next day, III went out on his own to investigate Yuma, still curious about how Yuma could fight without hatred. His first step was to watch Yuma duel Ryoga, only to be shocked when Yuma refused to hate or give up on Ryoga. After this, III proceeded to break into Yuma's house to investigate further, only to be distracted by the large amount of ancient artifacts in the attic and subsequently caught by Yuma's grandmother. When Yuma arrived home to intercept III, III's immediate response was to start excitedly infodumping about both the artifacts and his favourite Duel Monsters card (Chronomaly Aztec Mask Golem) at Yuma, followed by talking about his interest in out of place artifacts and his belief that out of place artifacts come from other dimensions. Yuma was briefly distracted by this, only to remember III's role in Haruto's kidnapping the previous day and called him on it. In turn, III apologized, genuinely regretting what had happened to Haruto, before admitting that he only fought on the power of hatred and asking Yuma about what drove him.

Yuma's answer: kattobingu, his belief in never giving up and always challenging himself no matter the circumstances, a belief he picked up from his missing father, Kazuma Tsukumo. III would have questioned this further, but ended up being invited to join the Tsukumos for lunch, where he got to watch Yuma interact with his sister, grandmother, and the family's adopted robot Obomi. Seeing the Tsukumos interact in a functional way that was miles apart from his own family's state utterly broke III, prompting him to leave in tears. Yuma went after III, only for III to state that he was going to devote himself to the Arclight family revenge in hopes of his family going back to normal after it was done. He then challenged Yuma to meet him for a duel that evening, declaring his intention to beat Yuma and get him out of the way, before returning home to prepare.

Once home, III deliberately asked to borrow some of Tron's power for the duel and was granted it in a ritual. The ritual was immensely painful for III, but he rode it out, gaining a boost to his crest based abilities. Tron also gave III two cards for the duel: "Number 6: Chronomaly Atlandis" and "Final Prophecy", though with the warning that Atlandis would take a toll on his mind and body even with the additional power to control it, while Final Prophecy, the 'Card of Destruction', would make it so neither duelist's safety could be guaranteed if it was played.

III accepted these terms.

That evening, Yuma met III for the duel as planned, at a jumble of under construction roads above the sea where no one (save for Yuma's friends who had tagged along to watch) could interfere. Upon starting the duel, III found that his newfound power allowed him to more clearly see Astral and proceeded to take the first move, quickly XYZ summoning Number 33: Chronomaly Machu Mech before declaring to Yuma that he had no intention of letting him use his 'kattobingu' spirit to win.

As the duel progressed, it soon became clear that III was starting to let his anger and envy get the better of him as he used Aztec Mask Golem, his favourite card, as mere disposable fodder to enable a high damage combo via the effects of Chronomaly Cabrera Trebuchet and Machu Mech while displaying none of his usual polite attitude, instead veering into something a bit more cruel. Yuma noticed this shift in dueling style and attitude and questioned what happened to III, only for III to declare that it was fine if he used his monsters as mere pawns in his strategy and that he intended to defeat Yuma no matter the price he had to pay to do it.

However, Yuma and Astral were able to take advantage of III's combo to reverse it and inflict damage onto III, something that, in combination with his perception that Yuma could never understand what kind of pain his shattered family was causing him despite his desire to protect and help them, pushed him further into his desperation and anger as he came to the conclusion that Yuma and Astral, together, were stronger than him.

And if Yuma and Astral were stronger together, then III would have to break them apart.

III used the powers of his crest to inflict a terrible illusion on Yuma's mind, one that caused him to believe he had never been told about 'kattobingu' or been given the Emperor's Key by his father, which resulted in Yuma becoming cowardly and unable to see Astral. Not yet done tormenting Yuma and Astral, III then proceeded to use his crest powers to seal Astral away, causing him to be chained to the top of a tower and unable to help in the duel, before having Machu Mech attack Yuma's monster, simultaneously causing damage to Yuma's Life Points and Astral's bindings to start hurting him. This marked the point where III started tipping fully into his rage as he took sadistic pride in his actions, outright laughing at the pain he was causing and using his crest to allow Yuma's friends to see what he was doing to Astral.

Terrified and rendered cowardly, Yuma quickly attempted to surrender on his next turn, only for III to outright refuse to accept the surrender and insist on continuing, forcibly skipping Yuma's turn to do so. With his opposition unwilling to fight, it seemed like a clear win for III-

-Until Astral intervened, using the last of his strength to help boost Yuma's confidence just enough for him to defend himself. Infuriated at this interference, III proceeded to use his crest to cause more pain to Astral, pushing more and more power through the bindings until they finally exploded, killing Astral.

Horrified, Yuma stumbled back and almost fell off the edge of the elevated freeway, only avoiding death as his friends rushed in to pull him back up, attempting to remind him of his bravery. III wouldn't have that though, and proceeded to seal Yuma's friends away as well (this time within a circle of crystals that cut them off from communicating with Yuma), rendering them unable to intervene any further as he taunted Yuma about how he was going to strip everything away from him.

III had missed one final source of interference though; the Emperor's Key. Yuma's long missing father, realizing his son's predicament but unable to physically reach his son to help due to being trapped within the Astral World after his sacrifice at the hands of Dr. Faker, appeared within the Key and used the power of the collected Number cards to forcibly undo most of the effects of III's crest, allowing him to finally remember his 'kattobingu' and realize everything III had done.

III was shocked that the Emperor's Key had negated his crest but was no less determined to win and protect his family, still seeing (the now grieving Astral's death) Yuma as a potential threat. To make things worse for III, Yuma, now determined to win once more, managed to XYZ summon his own Number (Number 39: Utopia) and used it to destroy Machu Mech. Undeterred and by now fully consumed by his rage, III then XYZ summoned Number 6: Chronomaly Atlandis, one of the two cards given to him by Tron, and then proceeded to activate its effect, allowing him to use Machu Mech from the Graveyard to power up Atlandis from 2600 ATK to a whopping 5000 ATK before launching an overpowering attack on Utopia-

-Or it would have been overpowering, if Yuma hadn't avoided it via Utopia's effect and proceeded to use Utopia to Chaos XYZ summon Number C39: Utopia Ray. III was startled by Yuma's ability to bounce back without Astral around as support, having assumed that Astral's death would render Yuma unable to continue, but pushed on anyways.

However, Tron's warning about Atlandis putting a strain on III was more than just words, as the effort of controlling it started to take its toll on him. This still didn't deter III as he allowed Atlandis to cut both his and Yuma's LP in half, but it did start to overwhelm him, causing him immense pain and the D-Gazer tattoo around his eye to start reacting to the strain and spread to cover most of his body. Realizing he needed to finish the duel fast, III attempted to attack again, only for Yuma to halt the attack and attempt to destroy Atlandis. Cornered and desperate to prove he could live up to Tron's expectations for him with his increased crest power, III activated the Trap card 'Final Prophecy', preventing Atlandis' destruction at the cost of destroying Machu Mech and, on the next turn, doing damage to both Yuma and III equal to Machu Mech's ATK (2400 damage). III no longer cared about protecting himself, instead ready to accept what was essentially a suicidal final strike to wipe out Yuma and, hopefully, save his family.

Final Prophecy, however, held a deadly secret; when activated, it began trying to punch a hole in reality to open a portal to the Barian World, which would have meant the end of the world if allowed to continue. Needless to say, III didn't expect this effect and didn't wish for the world to be destroyed, but was unable to stop it on his own.

Key words: on his own.

Working together, III shared the power of his crest with Yuma in a last ditch effort to revive Astral, an effort that carried great risk to Yuma but worked, bringing Astral back to life and allowing him to rejoin the duel. Yuma and Astral then merged together into their singular ZEXAL form and used their combined power (and Shining Draw) to finally defeat III, ending the effect of Final Prophecy before it could finish and saving the world.

Recognizing his defeat, III asked Yuma to save his family for him, claiming that Yuma was his 'first and last friend' before returning home, leaving both Machu Mech and Atlandis and a World Duel Carnival Heart Piece for Yuma as parting gifts.

After returning home, III's crest then claimed his soul as a result of III losing while controlling Atlandis, causing III to fall comatose, never to wake again unless his soul was returned. IV and V soon followed into their own comas, suffering losses to Ryoga and Kaito respectively during the WDC finals.

III's soul wouldn't be returned until after the end of the tournament, when Tron, in a last ditch effort to spare his sons from potentially dying with him after Dr. Faker unleashed his plan to steal all of the gathered Number cards after the tournament, released their stolen souls back to their bodies, allowing all three to reawaken from their comas. After reawakening, III and his family (including Tron, who survived his second near death) watched Yuma have a duel with Kaito before returning home, but not before Tron, for the first time in a while, called his sons by their true names once again: Christopher, Thomas, and Michael. (Though they would keep using their number names with consistency even after this, likely out of habit more than anything.)

The Arclights remained out of the action for a while after the WDC, researching both the Astral and the Barian worlds. Among other things, V managed to create special bracelets that would replace the crests, allowing the brothers their crest powers without the risk of their souls being taken again. They also kept track of the Barian's increasing attacks on Yuma and his friends, choosing to return to Heartland City via submarine once it became clear that they needed to step in. III was tasked with protecting Yuma in the wake of Astral being killed (again), this time by Number 96: Black Mist.

Arriving just in time to find Yuma being menaced by Mr. Heartland (now one of the Barians) and a Barian named Semimaru, III's first response was to throw the sword he had brought with him at Mr. Heartland, only missing because he teleported out of the way. He then teamed up with Yuma to duel Semimaru, telling Yuma that he would act as his 'sword and shield'. In turn, Yuma decided to let III have control of Chronomaly Machu Mech and Chronomaly Atlandis again, trusting him to hold onto the two Numbers.

However, Mr. Heartland and Semimaru had no intention of fighting fair; Mr. Heartland used his powers to drain half of III and Yuma's total Life Points and give them to Semimaru, causing Semimaru to start with 8000 LP while III and Yuma had only 2000 LP each.

Of course, when the rest of the family consists of a father obsessed with getting revenge against the man who wronged him, an emotionally distant eldest brother, and a second older brother who barely masks his sadism behind a veneer of kindness, it's not hard to come off as the nicest.

III is shown to be willing to do just about anything for his family. He willingly follows through on his father's orders to deliver a Number card to Ryoga, knowing full well that the Number card would try to take control of Ryoga on delivery. He also provides very little pushback on his older brother IV's behaviour despite being fully aware of IV's sadistic tendencies, standing by and watching quietly as IV tormented two duelists in a curbstomp of a duel. (And the one time he did object to anything IV did, it was because IV was deliberately showing footage of Haruto being tortured to Kaito, something that made III deeply uncomfortable due to his discomfort with torturing a child.)

At his worst, he's downright cruel, demonstrating a willingness to go out of his way to torture and eventually kill Astral during a duel in a fit of desperate envious rage, along with simultaneously tormenting Yuma in an attempt to hurt him/make Yuma feel just how alone III felt. Additionally, III has a tendency towards trying to sacrifice himself for the sake of others, best seen when he attempted to use the card Final Prophecy to force a tie between him and Yuma, fully accepting that this would mean sacrificing himself in the process. He demonstrates this willingness to sacrifice himself for others again much later, when he (alongside his brother V) willingly dueled Mizael in order to keep him from going after Yuma and Kaito, fully aware that the duel would mean his own death.

On top of all this, III also has a tendency towards intense jealousy of anyone with a healthier family than him; as shown when meeting the Tsukumo family only resulted in him running off in tears at how messed up his own family was by comparison, followed by resolving himself to follow his family's revenge scheme more closely.

So, you might ask, why is III like this? The answer is intense, undying loyalty.

III is ridiculously loyal to and protective of his family, despite everything. To that end, everything he does is generally done in the hopes that things will go back to normal/how things used to be once the revenge scheme is done. He has essentially put himself in the role of a protector or a metaphorical 'sword and shield', willingly doing whatever it takes to keep his brothers and father (and, eventually, Yuma as well) safe.

(Even murder. Even self sacrifice. III will dirty his hands and make himself complicit in his family's schemes and kill potential threats and sacrifice himself if he thinks that's what he has to do to see his family safe and restored to normal.)

That said, he does (mostly) maintain his polite, sweet nature. He willingly apologizes to Yuma for his role in the Haruto torture incident, deeply regretting what happened. He also ultimately places his trust in Yuma to save his family where he could not, explicitly calling Yuma his first and only friend in the process. However, that politeness can be twisted into something distinctly more smug when faced with an opponent, as he turns out to have a surprisingly sharp (but still technically polite!) tongue when he wants to. (See: III once responded to Mizael's complaints about his Tachyon Dragon being stolen from him by thanking him for the compliment.)

He additionally has a competitive side, choosing to continue dueling Ryoga with intent to win despite having been told he could just throw the duel after delivering that Number card mentioned above. This competitive streak served him well in the WDC tournament, when he managed to get all the Heart Pieces needed to advance in the tournament within the very first day, but doesn't prevent him from taking a more supportive role in Tag Duels in order to provide support and protection to whoever he's teaming up with.

Finally, III has a deep interest in history, expressing strong excitement at finding himself in an attic full of ancient artifacts. This ties to his sense of curiosity, something that drove him to go out of his way to investigate how Yuma could duel without hatred after meeting him for the first time. However, his curiosity towards history is tempered by his belief in 'out of place artifacts'/Ancient Aliens type beliefs, with III once expressing his belief that said out of place artifacts came from other dimensions. His Duel Monsters deck even uses the Chronomalies archetype, an archetype themed around historic artifacts with an Ancient Aliens bent.

(To be fair, III's father was investigating interdimensional portals, providing a reason for why III would believe in this stuff, but.)

As nice as he can be though, III is at the end of the day an Arclight, and none of the Arclights escaped being messed up by the family drama, not even the nicest of the lot.

-D-Gazer Tattoo: III has a special tattoo-like marking placed around his left eye that takes the place of a more typical physical D-Gazer. This tattoo, when active, allows III to see the AR effects used for duels.

III's tattoo appears as an orange mark surrounding his left eye when active, and also causes the iris to change from green to dark pink. It is not visible at all when inactive.

-Crest: III has a crest placed on the back of his left hand by his father Tron that allows him to access a fragment of the Barian's power, granting several special abilities. These abilities include being able to use Number cards without being controlled by the Numbers, being able to travel from point to point via portals, providing protection from having his Number cards taken from him, and, when preventing Astral from taking III's Number card, briefly allowed III to see the normally invisible Astral.

However, this crest comes at a cost; it is connected directly to III's soul and would remove his soul from him if he ever lost a duel while using particularly powerful Numbers, rendering III comatose.

In terms of appearance, III's crest is green and is shaped like a stylized flower. It is only visible when active and is not noticeable when inactive.

-Crest Bracelet: After the loss of his crest during the World Duel Carnival, III eventually had it replaced with a bracelet specially made by his brother V to emulate the powers of the original crests, without being connected to his soul. The bracelet allows III to control Number cards without being controlled himself, and even allows him to successfully summon Chaos Numbers, though not without pain to himself in the process.

The bracelet also has several new powers, including the ability to track both other crest bracelet wearers (read: his brothers) and the Barians, and, when synced up with another crest bracelet, the ability to produce an emulated Sphere Field.

III's bracelet is predominantly pink and white with gold trim.

-Duel Anchor: A device that can be used to force others into dueling III. It appears to be worn on his wrist and produces a red beam that, when generated, can be used like a whip to snare other people and prevent them from leaving until a duel is completed. The beam turns invisible once connected.

-Sword Fighting: III has been trying to teach himself swordfighting. He hasn't been able to get any actual teacher in due to his family situation though, so he tends to be more dangerous because no one with any actual training can tell what he's going to do. That said, he does at least have a few basic swordplay skills down, even if he also thinks throwing the sword is a good idea.

-Submarine Piloting: III knows how to pilot the Arclight family submarine and can do it as needed.

-Duel Monsters: III is skilled at Duel Monsters, and can hold his own in a duel.

-Ancient History Knowledge: III is deeply interested in history and ancient artifacts, and is able to identify and ramble about many artifacts on sight. This is slightly tempered by his Ancient Aliens beliefs, though.

-The Arclight family are upper class rich Brits.

-III is autistic with a history focused special interest, high empathy, some social awkwardness (he had no friends prior to meeting Yuma) and a questionable ability to handle change/belief that he can get his family to go back to normal when they likely won't completely do that. However, he's also undiagnosed and has no idea he's autistic.

-III's mother died when he was a toddler. Because he was so young at the time, he has no real memory of her.