Interested :)

I like the soulmates storyline idea a lot.

I've always liked 1-1s a lot, but been looking for someone with a similar ideaset to me to write with. Your ideas all strike a chord with me, but my preference is definitely the Soulmates one.

I prefer the idea of markings to imprinting. It means it can be a more drawn out reveal to the characters. Maybe the assassin would realise before the girl, for example. Maybe a brief kidnap whilst he wrestles with his ideologies of finding his soulmate and completing the contract, before he tells her.

Perhaps also we could consider the possibility that alongside the fact she's supposed to be getting married to this duke, whilst they're on the run, the assassin is also attempting to hide the fact he currently has a wife that he 'settled' for, because he didn't believe he'd find his soulmate.