Remus's and Sirius's interactions were not, from James's perspective, enough. Not only might they have figured that out from something Sirius had written to Remus - just as they might have seen something about him being an illegal animagus, if Moony hadn't been able to eat the paper quick enough, which was why he had asked for other proof - but anyone could have been able to tell there was something between them from the fact that Pads had immediately kissed their captive friend. Of course, that might have caused a repulsed reaction or something that they'd have seen right through, but only if the impersonator was an idiot.
It didn't matter anyway, since it was really Moony. Which meant there was a good bet the other secret they'd used to confirm his identity was safe, too. Thank Merlin.
"Moony," he said with a grin, and gave him a quick hug before handing over his pants and wand. They had a few moments for him to put on the pants, probably, because he could still hear fighting going on above their heads. For all that it had seemed like a while in his mind, it really hadn't taken them very long to get in here. "Backup, yeah, and a diversion. I don't envy whoever's been holding you captive, I'll tell you that."
Maybe it had been too easy. That thought sobered him: they weren't out of the woods yet. He led the way back up the stairs, footsteps quiet, checking for any wards that might have activated or re-activated as he went. No way in hell was he letting this rescue mission end in getting trapped in this godforsaken house.