Cursed ship: Willow Rosenberg/John Mitchell
Quite literally-- Mitchell would definitely run the risk of getting himself cursed! Well... Probably more like hexed in self defense!
If they met while Mitchell was still on the bandwagon, they could be good for each other. Willow might seem like a creampuff, but she's more than capable of defending herself. And she knows a thing or two about vampires!
They could bond over the fact that they both have profound darkness in their pasts, and sides of themselves they're deeply ashamed of.
If they met after the Box Tunnel 20 Massacre--
My original thought was that it would be a complete no go. Mitchell was a wreck, and everything had just fallen down around his ears. Everything he'd worked so hard for had turned to ash in a moment of weakness.
But the more I think about it, that might not be a deal breaker for Willow. She's seen darkness, and while she has trouble forgiving herself, the same can't be said about her capacity for forgiving other people.
This could be a story with a lot of depth and introspection and drama, and I'm here for it!