The New Avenger/Loki's Betrayal

At the Avengers Tower, The Avengers waited for Thor to come back from Asgard with their new Avenger. Loki was already a full-fledged Avenger so he was eager to know who Thor was bringing back. Would it be Sif? One of the warriors three? Who could it be? When Thor returned to The Avengers Tower, Loki was surprised at who Thor brought back with him. How could Loki get along with this "new" Avenger? Or will she tear The Avengers apart? Only time will tell.