Porthos had in fact noticed D'Artagnan hanging around the office a lot more often, lately. As if he doesn't get into enough trouble on his own, he has to come bother them while they're doing the mountains of paperwork Fury seems to throw at them. Not that Porthos minds, of course. He hates paperwork.
But today is a day off, and Porthos is puttering around the duplex, reading a little, or playing with the kitten. He answers the door, Bazin tucked into the crook of his elbow so he doesn't run out the door, and smiles when he sees D'Artagnan.