Board Thread:WARNING ALL USERS False Info\Spoilers/@comment-121.45.89.17-20130804051413/@comment-24.129.111.89-20140210161824

Well, if you think about it in the context of a wolf pack, and what we know from the canon of the show:

Talia was trapped in the house while Derek and Laura were out. Peter was incapacitated. The Hale line needed an Alpha. That power fell to the next available person... Laura. She was the next strongest.

When an alpha of a wolf pack is no longer able to perform his duties, the next powerful takes his place and he gets sent away. The Hale pack was also entirely family, from what we've gathered, until Derek began turning people and adding to the pack when it was his turn to be the Hale Alpha. There was a pecking order. Peter couldn't accept it in his state, so Laura became the next best thing.