Season 2: Till Death

Sam is lead away by Tess while Cat tries to comfort Dana inside the squad
car. The cops will tell Sam that not only did Gabe die in the blast, Dana did
too. Both are lies, naturally, but they’re necessary to get Sam believing that
he hasn’t been found out just yet so that he will lead them to the elusive evil
mastermind, Barnes. Gabe will pretend to be dead and go into hiding and Dana
has a choice. She can pretend to have died in the explosion, or she can go back
to him and live with him pretending nothing happened. She leaves to go into
hiding.

It seems clear that Dana heartrending realization about Sam applies to
Cat’s life. Dana, a skilled FBI profiler, failed to see that her husband was
turned after his years of imprisonment and brainwashing. Cat  did the same with Vincent and now is doing
it again with Gabe.