Dasher, for his part, occasionally goes, "Oh, is there another cat in here? HEY! A trash can to sniff!" but otherwise seems totally unaware of Buddha's presence. He's a much more energetic cat than Buddha, almost to the point of being high-strung, very chatty and LOOOOOVES his pettins. Loves loves LOOOOOOOVES his pettins! Ack! Too much pettins! *bite!* This tendency to get himself worked up into a frenzy is a habit we're going to have to disabuse him of — assuming he can even stay in the house at all.
Buddha has dibs, you see, and if it turns out that he just can't stand having another cat in the house, we'll have to find another home for Dasher. It should be easy; Dasher is one of the most aggressively friendly cats you'll ever meet, and while being FIV+ means he needs a little bit of extra care, it doesn't mean he's some kind of Death Scene From Camille cat who's going to steal your heart and then die on you.
However, Dasher's only been in the house for 48 hours and the two of them have not actually directly interacted yet except for Buddha having a hissing fit through a crack in the door, so we still don't know yet what the final result will be. We're going to keep trying for at least a week or two.