Lucas is a cocky and haughty person when first seen, he believes greatly in his piloting skills and is recognized as the undefeated European Junior Champion. He has the tendency to look down on his opponents as he showed when he made quick work alone to wipe out Team White Wolf commanded by Kenshou Matsunaga.
However, after Lucas' defeat at the hand of Team Celestial Sphere leader Wilfrid Kijima, Lucas is shown to have a big heart and more matured personality by accepting his defeat at the hand of his opponent.
Lucas is a very skilled fighter as shown by the fact that he is the undefeated champion of Europe. He demonstrated his skills by single handedly defeating three students piloting custom made units, with only a stock Jegan armed with a beam saber, without so much as a scratch.
Lucas traveled to Japan with his grandfather Josef, who promised him the trophy of the 7th Gunpla Battle World Championships for his birthday, investing a lot of money in the Flana Institute. However, during the semi-final round between Aila Jyrkiäinen and Sei Iori/Reiji, Aila betrayed Team Nemesis and told Lucas that if he wants to win at Gunpla Battle, he needs to play it himself. He took her words to heart and trained in earnest to be a proficient builder and fighter.
Seven years later, Lucas' skills had become so great that he became the undefeated European junior champion in Gunpla Battle. He moved to Japan to continue his studies at Granada Academy and participated in the 13th Gunpla battle championships under the alias Lucas Nemesis. When he first arrived at the school, the principal requested that he choose a Gunpla in the room and demonstrate his skills. He instantly chooses the Jegan, saying that it's a childish sentiment of his. The fight ends with the Jegan unscratched and his opponents defeated. The principal is thrilled to have seen it, realizing that they would have a far greater chance now to defeat Gunpla Academy.
During the tournament, Lucas was kept in reserves until the team is faced with the Gunpla Academy. However, before their quarterfinal match against Gabai Institute, Lucas, after witnessing Sekai and the Try Burning Gundam's last battle, got excited and decided to step in and do battle personally against Team White Wolf. After the battle, Lucas bumps into Sekai as he stepped out of an elevator. As Sekai steps in, Lucas asks if his injury has healed and before the elevator door closes, tells Sekai that he will fight him in earnest.
Team Von Braun ended up in an overwhelming victory as he took on all three Zaku of Team White Wolf singled-handedly, reducing them to scraps while he emerged entirely unscathed. In Team Von Braun's upcoming battle with Team Celestial Sphere from the Gunpla Academy, he picked Aiba and Tomita, two benchwarmers from the team as his teammates as he deems them to be suitable candidates in helping to carry out his plan.
As soon as they launched, Lucas ordered his teammates to stay at vantage points while he took on all three units by himself, using his Gundam's weapons at full power to take them on. After using up his particles, he would then retreat to either Tomita or Aiba in order to resupply on particles. While he was successful in shooting down all of Gundam The End's DE Fangs, he was left to retreat after the Peacock Smasher was destroyed by Adou's counterattack. He attempts to hide behind the large island, but the Transient Gundam's GN Partizan is powerful enough to blast a hole right through the landmass, forcing him into a full retreat to Aiba's point. At the same time, he ejected the machine's core fighter surprise attacking the G-Portent from behind using the hole, managing to get through her particle transformation field and fire off two beam sabers to nearly take her out in one attack. After a successful refueling, Adou and Wilfrid chase after him in a pincer attack. He wards off Transient's advance and kicks The End in the abdomen with a hidden heat dagger, gouging out a portion of its body. Adou counterattacks with a Dead End Finger and Lucas meets his attack with an I-Field. While preoccupied, The End uses its free hands to use its revolvers, but Lucas is quick to snatch them away with his Scissor Anchors, using his own weapon against him. Wilfrid jumps right in and slices the weapon in half to stop his attack. Cornered yet again, he uses a bright flash of light to distract Wilfrid and retreat to Tomita.
Unfortunately for Lucas, Celestial Sphere managed to figure out his plan before he could successfully stock up again. Tomita cancels the refueling to take on Transient and The End alone while Lucas would retreat to Aiba. Lucas apologizes as Tomita's machine is savagely destroyed by The End. He eventually spots Aiba but his machine is taken down in one shot by the G-Portent, lacking most of the damaged incurred by the core fighter attack. Though he finds himself surrounded, only Wilfrid takes him on. Lucas guesses he is either crazy or a serious Gunpla enthusiast as the two clash. Though Lucas begins to overpower the Transient, the machine activates its own special ability: Transient Burst, causing the machine to release a massive amount of GN Particles and push back with one powerful attack. When the light and smoke cleared, Transient is on its knees. While the Crossbone is still standing, Lucas is sweating and visibly exhausted, congratulating Wilfrid for winning as the Crossbone collapses in defeat.
Tomita and Aiba apologize for their mistakes, but Lucas couldn't be any happier, claiming it was a nice fight. He thanks Tomita and Aiba for being his supportive teammates as Wilfrid approaches him. He says that if the Crossbone's particle supply had been any higher, he surely would have lost, even with the power boost from the Transient Burst. Wilfrid says he will never forget this battle for as long as he lives, Lucas saying he'll "get his revenge", hoping for a future rematch. Their desire as mutual as they shake hands on it, looking forward to a rematch.
His coach then appears on stage and apologizes to Lucas, claiming they could have won if he had more sufficient resupplying and better talent in Tomita and Aiba. Lucas however defends them as his teammates did exactly as they were told, placing all of the blame on his inexperience and nothing more. While he takes his leave, Sekai meets up with him again. Lucas regrets that he won't be able to face Sekai like he promised, but still looks forward to another fight at the open tournament.
In the after-credits, Lucas is seen meeting Wilfred and Shia at Helsinki Airport in Finland.
- When he enters battle with his customized XM-X1 Crossbone Gundam X-1 Kai Kai "Skull Heart" Full Cloth", it is armed exactly how the Mobile Suit Gundam: Extreme Vs. and its sequel's renditions had armed it, with a Muramasa Blaster in the left hand, a Peacock Smasher in the right hand, and two Skull Head Units.
- Lucas uses a Jegan to show his skills in the same way Aila Jyrkiäinen did in Gundam Build Fighters.
- He closely resembles Tobia Arronax, the main character of Mobile Suit Crossbone Gundam. Him piloting the Full Cloth made his resemblance to Tobia go deeper as Tobia also pilots that suit.
- He is the only person in the GBF universe that made a custom Gunpla based on the non-existing improved version of its base model, the Crossbone Gundam X-1. The Full Cloth is also the only Mobile Suit that debuted in HG as an HGBF rather than HGUC.