Rex eyes the two of them with interest when he comes in-- a brief glance before turning his attention to the hodgepodge of technology (some he recognizes; others are as alien to him as his own technology must be to others) in the shop. He keeps his hands clasped behind his back as his eyes drift up and down the cluttered shelves. Some of the pieces are obviously broken, junk to some, but potential sources of opportunity to Rex. He reaches out to touch one eye-catching device in particular, a mechanical insectoid, vaguely resembling a larger version of his nanomites-- well, if they had wings-- and he can practically hear Iago scolding him already for wasting money on a broken little robot... He is, after all, on a budget, in Iago's words. Rex sees it as more of an allowance, personally. His mouth twists a little as he contemplates whether or not to pick it up.

And then a very real voice causes him to blink and look over his shoulder at the proprietor, who's motioning for him to bring a few devices over. Well, then. He furrows his brow slightly and glances between the xenian and the woman, then nods and picks up the broken mechanical insect. It's light in his hands-- lighter than it appears, actually. He picks up another device, something that looks a bit like a sonic screwdriver, although it's missing some paneling and the exposed insides have clearly been tampered with. Given the number of worlds and universes out there, Rex isn't certain that it's the same sort of device as what he'd encountered on the Barge, or if it's something else entirely. Hell, it could be a fancy lighter for all he knows. His eyes scan the shelves and settle on some kind of novelty... monkey thing.

...

Okay, Rex has to admit that it's baffling. So it'll do. He picks it up and carries them over to the two, arching his brow at the girl.

"Pop quiz?" he asks, his demeanor friendly enough for now.