Board Thread:Questions and Answers/@comment-26205387-20150324062737/@comment-5780397-20150324094644

It's possible. Hisoka's sexuality is twisted beyond human comprehension, so it is difficult to say. Personally, I think he is, but he might flirt with her just to get on her nerves, or simply be attracted by her the way he is attracted by powerful Nen users, though he never seemed intentioned to fight her; which make options 1 and 2 the most probable.