Board Thread:WARNING ALL USERS False Info\Spoilers/@comment-190.83.176.203-20130802171506/@comment-13844662-20130802182642

I dont think its going to last. She harmed/killed to many people as the darach.

1) Stiles' friend Heather and his dad (Who got kidnapped last episode) - Drive a wedge between Stiles and Derek.

2) Dr. Deaton and Scott's Mum (As seen in the next TW trailer) -  Drive a wedge between Scott and Derek.

3) The Darach tried to kill Isaac, Boyd and Scott in Motel California.  - Drive a wedge between Isaac (One of the last of Derek's pack, which would cause him to most likely join Scotts pack).

4) The Argents wouldn't allow the Darach to live after killing so many people.

So if Derek stays with Jennifer he losses any help from Scott or Stiles,  most likely Isaac leaves the pack and gets hunted by the Argents for being with the darach.