I've been stuffing my shirts into the sleeping pouch (without them inside, of course) so they can become more acclimated to my scent while they sleep, and I've noticed some progress.
Batman will come to me when I'm near the cage, but still tries to nibble any appendage that gets near enough to him--I really do wish that wouldn't happen, but I don't know what to do about it. He'll gnaw at my wrist bone if I try to hide my fingers. Recently, I've been touching the top of his head when he does it, and I believe it's turning into a sort of a game. I've read that it might be an attempt to groom me, but when I let him nibble, he'll keep going and scrape my skin off.
Robin allows me to pet him, despite he tends to be the shyest of the two.