Unexpected [avengers a.u.]

Christina Barton wants nothing more than to follow in the footsteps of her parents: to work for the SHIELD agency, and to avenge their deaths. After managing to gain the approval of protective big brother Clint, she finally receives the title "Agent".
However, her first days in the agency are marked with upheaval and trouble for New York, and the world, when Loki makes his attack. When her brother is taken under Loki's control, Christina is forced to shoulder the responsibilities of a much senior agent. She'll do anything to get her brother back.
Anything.
Even if that means having several run-ins with the confusing, and intimidating, prisoner from another world.

-DISCLAIMER-
I do not own any of the Marvel characters, or their individual plotlines as established by the movies or comics. I do, however, own the character of Christina Barton, as well as all her plotlines as established by this story. I also claim the ideas and events that occur after which the timeline set forth in the movies ends. Please do not use these ideas or my original character without my knowledge or consent. The character of Christina Barton may be used in artwork or fanmade covers or edits if proper credit is given. (i.e. Please mention me/provide a link to my story) Additionally, if you make something, please tag me or let me know, as I'd love to see it. :) (I don't want to sound like I expect people to make things; I've just been asked before, so I thought I'd mention it. :))