He's not completely perfect, but with over 20 bored geniuses in his head playing Joseph's little 'your next line will be' is fairly easy, particularly when he knows the person well.
Buffy the Vampire Slayer/Iron Man Crossover (Self-Made Hero)
Summary: Buffy finds Xander testing a couple inventions and spells out.
Word Count: 240
“W-what are you doing?” Buffy asks on walking in on Xander staring fixedly at a table with holograms. Whatever it is, she can’t tell just by looking. It’s been harder to read Xander since. Mostly what he’s doing, but sometimes how he acts.
“Me ‘n Zathras were trying to figure out how they played Dejarik. So far, no happy.” He shrugs. “At least I’m getting hologram practice. See, tech hasn’t advanced to the point that we can really use holograms willy nilly, but they’re useful for a visual, so I’ve been working on adapting an illusion spell. That’s going well at least.” He anticipates her next question. “I ran the spell and changes by the G-Man, yeah. I’m not suicidal. Or reckless. …Most of the time.”
“That’s getting really freaky,” she admits, earning another goofy grin. “Zathras?”
“Zathras very pleased to be meeting you,” an unfamiliar voice joins them, and she blinks.
“Meet one of two AIs I’m developing—and yes, Buffster, I’m being careful, to the point of a self-destruct as a last resort option. I haven’t forgotten Moloch. The other is White Star and she’s kinda the combat expert. I figure it’s better if I’m not having to decipher Zathras’s speech during battle no matter how cool it sounds.”
“Zathras be making suggestion, hmm, yes. Is not enough information for Zathras or Ranger One to play this game,” the program adds.
Xander sighs. “Yeah, but chess is boring.”