"All right then. But you realize I'll have to put you down in order to arm-wrestle him or anybody."
"You better. Where is this demonic competitive fellow?"
"Hello there. Rumor has it you might be able to arm-wrestle a vampire and win." Nathan puts the Joker down and spreads his hands. "I am a convenient vampire."
"Someone will have to explain 'arm-wrestle'," says Aianon, "but I think that could be fun."
"We find some surface - not Pattern's little genomics lab over here, maybe a rock, outside - and plop our right elbows down on it and -" He demonstrates the relevant grip on his mate. "Try to force the other's hand down onto the rock or whatever."
Aianon starts slow, testing Nathan's strength. He is careful not to dig in his claws.
Nathan's hand stays exactly where it is. "Am I trying to win or do science?" he asks.
He keeps increasing the pressure from his side. It doesn't go up as smoothly as it would with a vampire, but he's definitely getting into vampiric range.
He switches goals from "keep hand where it is" to "slam Aianon's hand onto the rock". This isn't as automatically decisive as it would be with any non-supernatural strength, but it is sudden and forceful.
Their joined hands sway abruptly in one direction, and then somewhat less abruptly in the other. Aianon doesn't have perfect control of exactly which muscles are exerting how much force; he crushes Nathan's hand a little.
"A little less with the squeezing?" Nathan says, wincing.
"Sorry," he says, flicking his tail from side to side, and tries to squeeze less. Which also leaves their hands more or less vertical.
"Although the fact that you can meaningfully squeeze my hand is interesting," comments Nathan, still pushing.
"Is it?" he wonders, still pushing back. Their hands waver back and forth a little; the force he applies isn't consistent.
"Yeah, at home vampires can be hurt by three things. Vampires - or our relatives, if they get a chance - and werewolves and fire." Pause. "Starvation can also get us but it's slow. Usually."
"Demons can be hurt by many things, but killed by few," he says. "Unicorns. Certain magics. Unicorns no longer burn me; I have not tried the other."
Nathan kisses back. His distraction does nothing to lessen the force of his wrestling arm.
The demon laughs. His distraction makes him forget not to squeeze, very very briefly before he remembers again.