User blog comment:Brian Linder/Wikia Fannotation: Avengers: Age of Ultron Trailer/@comment-8284722-20150113181257/@comment-4651179-20150113191549

The person has earrings and ear piercings, long eyelashes, red or light brown hair pulled back, and overall femenine features. Not Loki. The person is also wearing a jacket, not your everyday Asgardian attire.

In addition to the Black Widow being experimented on. Based on the previous trailer's footage of ballerinas, and her haircut, it can presumed is a flashback of her origin at the hands of the USSR.