User blog comment:Aegis Runestone/Does anyone else dislike Lucy being... *spoilers*/@comment-1703264-20120419021702

I think that Lucy did become disillusioned about the Assassins until 16's death because even though she said that she could never let 16 leave, she also promised to protect, but she ended up failin', and so she had a realization on what the Templars really stand for, and decided to switch back to the Assassins, but still kept her "affiliation" to the Templars in order for them to not suspect her.

P.S. I'm makin' an Assassin's Creed movie about 16, and Lucy is still an Assassin cuz I wrote the script before the DLC came out, and I also decided to make 16 and Lucy siblings.