"He may be prickly, but does he sleep with men?" If he doesn't, then Jaskier doesn't have any chance. If he does, then Jaskier is more than happy to try. If Lambert isn't interested, well Jaskier still has Geralt and now Eskel, so it't not like he's lacking in bed partners, just in variety.

Coen is an interesting suggestion, however.

Jaskier isn't going to go anywhere near the sorceresses. That seems like it would be far too much drama for him.