Aerie is a member of the Avariel, a race of winged elves, who was crippled in the sense of having her wings cut off, forcing her to remain earthbound for the rest of her life. She's a playable character and potential love interest in the game Baldur's Gate II: Shadows of Amn and its expansion Baldur's Gate II: Throne of Bhaal.
Aerie's earliest life was spent apparently happily in Faenya-Dail, one of the few remaining cities of her people. However, she was captured by slavers (apparently still at a young age) when she swooped down from flight to rescue a child fleeing from them. They sold her to a circus, where she was kept on display and in a cage so small she had no room to stand, much less stretch her wings, which eventually became diseased. The infection threatened her life, which was saved in a very crude manner by painfully chopping off the wings. The circus had no more use for her after this, but the gnome called Quayle continued to take care of her as he had during her captivity—though he could do nothing to restore her wings. The pair of them continued traveling with a circus that may not have been the same one, until it arrived in Athkatla and set up the circus tent in Waukeen's Promenade. While they were there, their disgruntled illusionist Kalah used powers of unknown origin to turn the inside of the tent into a world of deadly illusions, turning Aerie into the likeness of an ogre and chaining her magically to prevent her from escaping. It is at this point that the player character's group arrives at the Promenade, and has the option of exploring the tent.
Aerie comes across as very naive, caring and needy at the same time. She is a cleric as well as mage, learning from Quayle to serve the gnomish god Baervan Wildwanderer; she no longer feels quite worthy of approaching her old winged goddess Aerdrie Faenya. Her wingless state has left her feeling generally unworthy and useless, which she may get over to varying degrees as the game progresses. Her confiding about her problems to a male player character can potentially lead to a romance. Besides of this preoccupation with her own problems, she's very empathetic to anyone else's plight and always eager to help. If in the party together with Minsc, she may develop a special bond with him, becoming his new "witch" in place of Dynaheir whom he couldn't protect. If Haer'Dalis is present, she may also fall for him, possibly ending up having to choose between him and the protagonist.
In Throne of Bhaal, Aerie may have the protagonist's child (in a very accelerated time frame). If they are together at the end of the game, he will subsequently help her find Faenya-Dail and her family again some time in the future. Otherwise, she will go on a crusade against slavers.