Ok, so Cosmo was kind of touched that Kate referred to herself as Comrade Beckett. For how they tended to be utter smart-asses to each other, there really was a close and, while unlikely, natural friendship there.
"In most realities, the undead are beink killed by destruction of their brain. Nothink else seems to work permanently. Be careful, Comrade Beckett... do not let them bite, scratch, or otherwise break your skin. Cosmo doesn't fancy tummy rubs from an undead friend..."
Giving a pathetic little whimper (he was still a dog, you know...), Cosmo paced back and forth before thinking to himself, "Please, comrade Beckett, do not be gettink yourself killed...