You 'graciously' let him go first

"since I preposed it, it's only fair you go first." you hold back a chuckle at the imp's look of pleasure. You were not planning on losing.

The imp stayed hovering with his too-small wings as he grabbed onto his still sizeable shaft and started pumping, panting heavily already. He so focused on his own pleasure he didn't notice you moving behind him. You reach round him to grab his hand around his shaft and begun yanking his hand faster.

"W-what are yo-oooh- doing?!" the imp was practically being lifted by his cock, his bat wings could barely keep up.

His face was sweat and lust, his tongue lolling out, drool flying everywhere, and his eyes completely unfocused. His cock felt like it was shrinking a small bit everytime you pumped him up and down.

His whole body clenched, almost falling down, and then a massive load shot out, caking the wall in front of you with sticky white seed. The volume was immense, and spurt after creamy spurt covered the previous. Your hand was covered in it.

"H-hah I did it, I-I won" the imp wasn't even looking at you, lost in a post nut haze.