Success?

Melissa feels the cum slide from you cock an instant before Beast's fills her pussy. She swallows the first load to be sure, then locks her lips around your cock and sucks with gusto. Her eyes light up as you feel her pulling your cum into her mouth. You're spent as she pulls away, opening her mouth wide to show you the thick black cum that coats her tongue. She licks a few drops from her lips and then locks her eyes on your are she seals her mouth shut and swallows.

Pushing you to the floor, the succubus to be demands, "More. Need to fuck more."

Beast deflates and disengages from Melissa's cunt. Melissa positions herself over your still hard dick and takes it into her in one stroke. You manage to direct Beast to move over you and Melissa dives onto his cock. She's barely satisfied when her final hole is filled by your tail.

Melissa rides you in that position though four orgasms. Two each from you and Beast. She's a sloppy, sweaty, cum covered mess, as she lays beneath you with her legs spread wide. You feel her pussy throb. The heat from her loins rises as her soul burns within her and passes into the depths of Hell.

She looks at you with a satisfied smile as her eyes darken and red slits replace the pupils. She glows with increasing heat as her skin reddens and her figure swells to ridiculous proportions. Pulling you into a kiss, you feel her lips swell into perfect cocksucking pillows. Tongues wind together as you kiss, and when you finally break from her, a much longer, black tongue slips into her mouth as the tip splits into a fork. Melissa smiles at you revealing longer canines and shivers a bit as horns erupt from her forehead. She spreads her bat wings and rises off the floor, offering a dainty, clawed hand to help you up.

You stand next her and smirk, appraising her new form. Melissa smirks too, but only for a moment, before her countenance turns dark, and she slaps you across the face. HARD!

You lick off the blood that her blow has caused to flow from your lip.

"You evil bastard," she shouts, "you think you can dominate me?"

The trials you put Melissa to have clearly made her into a powerful succubus.

"We'll see who's the bitch and who's the bastard!"