This is an original character from someone's fanfiction. her name is Rosa Petrovsky, as you can see she is General Petrovsky's daughter. She is an ex-Cerberus, and now she is a squadmember of the Normandy's new commander, Javik =P
Although she has limited appearances while there were other several important original characters in that story, but it seems like she has a lot of fans among the readers. I suppose that's because she is a Tsundere LOLI with sliver hair,and she is a N7 shadow with biotic power--Adorable and awesome!