>>807492
either/or, he's fine with both
he doesn't feel the physical sensation of sex (he's a mushroom) but it's more the *idea* of penetration (in any sense) that'd get him going. something about how being inside each other is the closest you're going to get to becoming one/symbiotic without doing so in a literal sense (doing that isn't possible with faunal lifeforms like humans)
i don't imagine it would feel particularly pleasant, though - unless you find a way to warm his body up it's going to be cold in there, like it would be if you stuck your dick into damp soil on a misty morning
him topping is only a little better - it's still cold, but at least it'll warm up eventually.

he also will encourage you to eat him. don't do that. they'd be able to pour out your liver at the autopsy.