Wait, did pyro cum? Can pyro impregnate someone? Woulf the baby be half fae or something? Does this mean pyro has bodily fluids hiding in the flame?
The babby would be half-djinni, so much like the fire genasi of D&D or the Ifrits of Pathfinder, they would have a fiery bent while being also kinda human. Hair that always seems tousled, possibly made of heatless flame, the little horns, glowing eyes, perhaps skin that harkens to images of flame (like with an otherworldly shimmery bronze sorta tone, nothing like any real human naturally has). Yanno, something overtly supernatural and a mixture of human and djinni.
Pyro's body works pretty much the way most folks', do, except all of the fleshy bits are made of solid flame. It's all very nonsensical. He bleeds, he drools, he comes, and he eats and drinks and uses the bathroom. He's just had to, yanno, do all of that in secret before. I mean he still probably poops in secret most people don't want others hangin' around while they deuce, lol.
He really, really likes sweets. <3