The Summoning Went Awry - Fantasy, Slave-Domination, Incest?

[Top Cat]

Caleb is an amateur Summoner. He's had some brief, perfunctory Mage training, but has more ability than sense or experience. He's ambitious, though, and he got his hands on an incomplete design for a Succubus summoning circle. He's certain that he can finish it right... and who wouldn't want a sex demon as his obedient slave?

Needless to say, it doesn't go quite right. As a result of his poor design alterations, he ends up summoning someone he knows - his sister, mother, aunt, maybe a close childhood friend that he hasn't seen in a few months? Regardless, whoever he summons has the body of a succubus - a sexier version of their normal body - and with all of the other features of a succubus. The powers, the immortality, and especially the incurable lust...

He'll have the question of whether or not to use her as he intended. Can he be sure that it's really her, or just a succubus trick? She'll have the heavier burden - her body wants him in it, but her mind may not be entirely on board with the plan. And while she is bound to obey any direct orders he gives, she still has her own mind and attitude.

As usual, please respond via PM, not in-thread.

Will they fall into the Master/Slave relationship that he originally intended, or will they work to try to free her (while still probably having sex regularly)? Trying to undo the summoning is hugely risky - he has no idea what he did wrong, after all, and might end up sending her to the Demon Realms that Succubi come from instead of separating her back to her normal self.

Lots of options here. I'd prefer more story-heavy plans, and I especially want feedback from my partner on what kind of storyline they want to see here. This could be high fantasy, low fantasy, urban fantasy, or even futuretech fantasy - what sort of world did this happen in?