Syntaxeme
Having made no deals to secure his power, Alastor has spent his afterlife in Hell a fairly average Sinner with one particular unique ability: a voice that makes him all but irresistible to most demons. For decades, he's been bound to Rosie's service, using his silver tongue and natural charisma to help her negotiate her contracts.
Of course, his talent is no match for someone like Vox. But their first meeting makes an impression nevertheless. Vox finds himself fixated on Alastor and compelled to possess him. So he does what any businessman would and makes a deal to buy Alastor's soul.
A deal with Rosie, that is. After all, Alastor's soul is no longer his own property.
Blindsided and bitter over the forced upheaval of his afterlife, Alastor plans to rebel in every way possible. His brattiness does nothing to deter Vox, who's determined to find the obedient pet hidden underneath. Both are thrown very much off-balance by an unexpected affection mixed into their antagonism.
But affection doesn't equate to peace. Even if they do want to navigate the completely unfamiliar territory of a partnership, there's still the risk of driving each other crazy along the way.