What the Joker was doing—what they were doing, together—was helping Alice understand himself better and accept himself more. It was important to him to do it, not just because he wanted to have that experience, but because he wanted to learn from it. Well, 'learn' might not be the best word. Try: he wanted to change in the ways that that experience made him change.
Apparently, his power was backing him on that.
Bella chews on her lip. "How smart and/or prognosticatory is this power? Is it liable to start steering him towards things instead of just resisting attempts to remove him from things?" [I'm planning on turning him into a vampire,] Bella adds privately to Lazarus, [for Christmas, it's a surprise - sometimes vampires have magical improvements after they turn. So if it doesn't do this now but that looks like a way it could change...]
"...Well, it can't do what Alice doesn't or wouldn't want it to. Can't or won't, it's the same thing. So... that might be reassuring?"
[It doesn't look to me like this power wants to change what it can do,] he says. [But I wouldn't have said it would protect experiences he was having, either, and then it did.]
[Well, if it wants to do what he wants, then him being a vampire can only improve it. I ran the idea by my alt's precog-sister and precog-sister says that his magical vampire mate bond thing will stabilize on me, no problem.]
[I doubt he'd mind you watching. It'll happen three days after I start the process. However, the entire thing is also going to hurt in ways human beings don't even know how to hurt, so whether you'd want to be around...]
"We're talking about your Christmas present," Bella says, floating off the floor a couple inches to kiss his temple. "It has some magically interesting properties."
Lazarus's blush kicks up a few notches, to catch up with all the blushing he didn't do because he didn't know Kolya could hear that entire conversation.
Bella laughs hard enough that she can't even go on kissing Alice anymore. And she doesn't stop when he fades out, either, because she just doesn't have that much self-control.
"I don't know to what extent answering that question would violate my agreement," muses Bella.
"I've been here the whole time," he says, addressing Alice directly. "You just can't see me. I, however, can see you."
"That's funny, because Alice can see my alt's bodyguard who has a comparable power," Bella muses. "I really need to bring you there with me, sometime, Lazarus."