Linus Claude serves as a Neathian brawler within the Castle Knights faction, wielding the Pyrus attribute. His childhood-forged bond with initial Guardian Bakugan Neo Ziperator ended tragically when Gundalian forces captured Neo during a critical mission to deliver him to Fabia Sheen, as Neo possessed a vital element. Neo’s subsequent demise shattered Linus, culminating in an emotional vision where Neo reassured him before transferring the element to Drago. This loss positioned Linus as the series’ second brawler to endure a partner Bakugan’s death, following Joe Brown’s loss of Wavern.

Ren Krawler entrusted Linus with the Pyrus-aligned Rubanoid as Neo’s replacement. Initial friction defined their partnership, but shared determination to avenge fallen comrades—including Neo—solidified their alliance during Neathia’s war against Gundalian invaders. As a Neathian defense force member, Linus fought alongside Battle Brawlers and Castle Knights in pivotal clashes against adversaries like Zenet Surrow and Gundalian Soldiers, though his inexperience prevented on-screen victories.

Deleted scenes reveal Linus preparing meals for allies using his mother’s recipes and tending to Rubanoid in a treatment tank, reflecting his loyalty to Neathia and comrades. He honored Ren’s request to safeguard Rubanoid beyond the conflict, pledging ongoing care before the Gundalians’ retreat. Linus exhibits a respectful demeanor and bears a noted resemblance to Star Trek’s Spock in Neathian form. He also stands as the first depicted Neathian brawler utilizing a non-Haos attribute.

Post-Gundalian war, Linus continued serving with the Castle Knights on Neathia, parting ways with Dan, Marucho, Shun, and Jake upon their Earth return. His narrative explores resilience through loss and the painstaking cultivation of trust with Rubanoid, underscoring his steadfast role in Neathia’s defenses.