PIxie is a member of the new x-Men team. She first appeared in the comics as an unknown mutant in New X-Men: Academy X: #5 in 2004, and had her identity revealed and joined the X-Men a few issues later. Here’s a bio http://marvel.com/universe/Pixie_%28Megan_Gwynn%29
Pixie’s abilities are that she has pixie like wings that allow her to fly and pixie dust that causes hallucinations. An incident involving one of the other X-Men, Magik, ended up in Pixie loosing a piece of her soul, and as a result she could call upon the Souldagger, which is her main weapon. She was also given a bit of magic which she uses for teleportation.