Eugene serves as a supporting character in the Sword Art Online series, prominently featured in the Fairy Dance Arc as the commander of the Salamander forces within ALfheim Online. Recognized as one of the game's most powerful players, his reign ended when Kirito defeated him in a duel during a conference between Cait Sith and Sylph representatives, resulting in his agreement to withdraw Salamander troops from the conflict.

Later, Eugene assumed leadership of the New Aincrad clearing army following the launch of that new game environment. He created an eight-hit Original Sword Skill, Volcanic Blazer, demonstrating his ongoing combat skill. During the Mother's Rosario events, Eugene attended a barbecue at Kirito and Asuna's home, extending an invitation to Yuuki and the Sleeping Knights to join his faction, which they declined. He was present among the large gathering of ALfheim Online players during Yuuki's final moments.

Eugene is listed among the characters appearing in Alicization - War of Underworld Part 2.

His background identifies him as Lord Mortimer's brother in ALfheim Online, a connection assumed to exist in real life. Personality-wise, Eugene exhibits a strong desire to face formidable opponents, evidenced by his choice to escalate a duel with Kirito to a deathmatch after witnessing Kirito's resilience.