Ai Shi's history:
When she was eight she had her soul imprisoned inside a necklace that she wears around her neck. she killed her village after that. she was forced to join the Akatsuki by Deidara. (who she secretly likes but pretends to hate him, along with everyone else) Ai doesn't really hate the Akatsuki members, she actually likes them and will do whatever it takes to keep them safe.
Ai's personality is cold and distant from the start. but in time, Deidara brings out the best of her, even though most of the akatsuki are afraid to get near her they start to warm up to her.
Ai's powers: she has the power to control a ghost like creature named tur. Tur is a complete idiot, he can act like Tobi most of the time. but under Ai's command he can steal your soul in a heartbeat.
Ai's weakness are the Akatsuki, she'll do anything to protect them and water. she can't swim...at all.