Nobuyuki Sugou
須郷 伸之
Background
This bio may contain spoilers.
Originally selected by Asuna's father to marry Asuna, he was adopted into her family on her father's wishes. He attended the same school with Kayaba Akihiko, who he viewed as a rival. During the Sword Art Online incident, he took advantage of the chaos to steal test subjects for research along with Asuna. In ALfheim Online he adopts the persona of Fairy King Oberon.
As the Fairy King Oberon, he keeps Asuna locked up in a bird cage at the top of the World Tree. In the real world, he confronts the powerless Kazuto by voicing his intentions of wedding the unconscious Asuna. While keeping Asuna locked up in ALO, he constantly visited her just to fool around with her. From his actions, one could say that he is a pervert.
(Source: swordartonline.wikia)