Seles Wilder

Seles is the half-sister of Zelos Wilder. She has been easily susceptible to illness for most of her life, and because of her poor constitution, she relies on an Exsphere through the events of the first game to allow her to function normally on a day to day basis. Despite the fact that they were born to different mothers, Zelos and Seles still loved and played with one other when they were kids, not caring that they were not fully related, as claimed by citizens of Meltokio. One snowy day, Seles's mother tried to kill Zelos to make Seles the next Chosen; however, the spell she shot at Zelos instead hit his mother, Mylene Wilder, killing her. As a result she was executed, and Seles was sentenced to house arrest in the South East Abbey for life, although the official reason given was that it was for her health.

(Source: Aselia, Tales of Wiki)