Well, it's been an adjustment period. Orbit's not really himself since the kitten's arrival, though now and then we do see a spark of his old self.
During the night he came up onto the bed and cuddled with us the way he always did, and we even got a headbutt or two in the face. I know the old orbit is still in there, he's just letting us know he's not very happy with this new temporary situation.
He's hissed at the kitten a few times, and whenever he hears him crying he stares with large, suspicious eyes, in the direction of the new sounds. Our current living arrangement doesn't really allow for this to go from the "F" word to the "A" word, and I'm hoping we'll be able to find a decent home for the poor little guy once he gets a little bigger.
I'm sure orbit will bounce back, but I'm hoping this doesn't cause any permanent health or emotional issues at his... advanced age. He's sitting on the floor behind me right now, where he's been spending most of his time when not hiding under the bed. His hearty vocalizations and near-constant need to be in a lap have pretty much stopped, but I'm sure this is normal, and he'll either get used to it, or return to the way he was once kitty finds a home.