It's been a while...meaning since the episode aired because I've been purposefully avoiding watching that scene ever again so I may get something wrong, since I watched the moment Theo "killed" Tracy. (She's not dead, stfu) But remember the second he goes to kill her and she digs her claws into his shoulders? Of course that means she was trying to stop him but with a Kanima, that also means she tried to paralyze him. We don't really know if it worked or not since the camera showed Deucalion right after, but what if it did? What if Tracy really did manage to paralyze Theo the moment before she died? That would mean he would have had to sit there for however long it takes for paralytic venom to get outta his system, and know....just know he killed his last remaining and undoubtedly loyal Beta. Imagine what must've been going through his head. It could be argued whether or not the reason Tracy was so loyal was because of the Kanima side of her looking for a master (Master/slave kink wouldn't even be roleplay for them) but we also need to remember that Theo was one of the first, if not THE first person to ever look at her with something other than pity or regret. He wanted to help her, and I'm not saying Scott, Lydia, Malia and the others didn't want to help her but Theo needed her in a way the others didn't. He didn't want to help her just because it was the right thing to do, but because he truly felt she would make a promising ally. Now let's take all that and add that to how Tracy absolutely trusted him and believed he would stop the Beast, and just the way she looked at him after he kissed her. In my opinion, I think she really did love him. And then shit hit the fan. Imagine Theo, sitting there, forcing his paralyzed limbs to move while trying not to look at her body. He needed a pack...but then again, he was the reason he lost them in the first place.