Originally set up by Asuna's father to become her husband, he was adopted into the family as a result. He went to school with Kayaba Akihiko, though their relationship was more rivalry than friendship. When the Sword Art Online incident happened, he saw an opportunity—he and Asuna used the chaos to collect test subjects for his research.
Later, in ALfheim Online, he reinvented himself as Oberon, the Fairy King. He imprisoned Asuna in a birdcage suspended at the top of the World Tree, and while she was trapped there, he made frequent visits that were less about guarding her and more about his own gratification. In the real world, he tracked down Kazuto (who was helpless at the time) to inform him of his plan to marry the still-unconscious Asuna. His behavior throughout makes it pretty clear he's a creep with serious boundary issues.
Content compiled by AnimeList.moe from publicly available sources.
