If you want to talk about tragic characters in Bioware games, then look no further than the Lady Aribeth de Tylmarande from Neverwinter Nights.
Lady Aribeth de Tylmarande was a half-elf paladin of Tyr, the Blind God of Justice. She is said to have been born in Thundertree, a town in the Neverwinter Woods of uncertain parentage; some say a union between half-elves, others a moon elf and a human. The village was wiped out in an orc raid leaving her the sole survivor of the massacre. Vowing vengeance, she hunted down the perpetrators and slew them all. Unsatisfied, continued to hunt and kill orcs in an obsessive quest until she was trapped in a sudden blizzard and rescued by a one-armed man she believed to be an avatar of the god Tyr, who took her to a monastery of Ilmater. Recovering her health there, she learned to be a paladin, gaining such fame that when she moved to Neverwinter, she was named to the elite bodyguard of Lord Nasher Alagondar, being the first woman and first non-human to be so honored. There she met and became engaged to Fenthick Moss, a cleric of Tyr in the Halls of Justice.
In the original campaign, Lady Aribeth was chosen by Nasher Alagondar to be in charge of the investigations surrounding the Wailing Death. She began training adventurers at an academy to combat the forces behind the plague, and after the Waterdhavian creatures needed for a magical cure became scattered throughout the city, the hero, who was an exceptional student at the academy, was placed by Aribeth in charge of tracking them down.
It was revealed later that her lover, Fenthick Moss, was executed due to association for the creation of the Wailing Death. This affected Aribeth, and eventually she fell becoming a blackguard in the service of Morag. The player must eventually take her down, but has the chance to convince her to stop (it’s a very difficult persuade check).
Later, in Hordes of the Underdark, the player meets Aribeth again as a tormented spirit, and she joins the quest to stop Mephistopheles. During the last battle, if Aribeth is in the party, the demon lord will use his charisma to turn Aribeth against the player. Successful persuade checks (higher than when forced to persuade Aribeth in the original campaign) will keep Aribeth on the path and she aids in defeating the demon lord.
In Neverwinter Nights 2, Fenthick Moss’ spirit is encountered in the Tomb of the Betrayers. But no mention of Aribeth is made. It is assumed that Lord Nasher and the citizens of Neverwinter chose to forget her, because she was an ugly reminder of the evil that rests in them all. It’s also interesting that no mention of the hero of Neverwinter who aided in stopping the Wailing Death (the player) is also made. It’s believed that the hero was also erased by Nasher, and assumed the hero came to the defense of Lady Aribeth.