Tagged demon summoning

What begins as a young warlock's desire to prove her ability turns into a debauched display. Sarah, recently having finished her mentorship with the refined mistress Valeria von Stesse, has summoned and, just barely, bound a large demon - a winged eredar. Many have tried this before, and many have been consumed by the power of such a creature. To keep her place in the warlock's lodge, she must prove she controls it. What better way to do so than to fuck it?