How do you deal with someone who just wants to mess with your mind, and can't step up or commit?

At the beginning of this year I started working with this guy. For Fluther purposes we’ll call him Neil. Neil and I did not get along AT ALL. We got into several verbal fights and even threw things at each other sometimes. After the first couple weeks of getting to know Neil, we stopped fighting and became really friendly with each other. I even started to have a little bit of a thing for Neil. The more we were around each other the more the other people at work started noticing that we were no longer the battling old crows (not that either of us are even remotely old) that we used to be. Neil and I could tell exactly what was going on in the other’s head with just a quick flash of the eyes (oh, how I miss those eyes!). He even chewed me out once for “flirting” with some guy who he didn’t know was actually just my cousin, and I was not, by any means, flirting with him. One of the other girls at work asked Neil he if was ever going to take me out, she even offered to work his shift on a weekend so we could go do something. I don’t think they knew I was about ten feet away and could hear everything they were saying. Or maybe they did know and just didn’t care. Neil was very enthusiastic about the idea. The other girl and I talked about it later, she said she could tell that Neil really liked me and she thought he would probably ask me out any day. Then, about two weeks after that, out of the blue, Neil tells us all that he’s going away for three months, but when he comes back he’s going to want his job back.
Our boss says she’ll give him his job back, because he’s a good worker and we all adore him. So Neil will be back in about 3 weeks. I am QUITE nervous. We haven’t talked this whole time. I’m pretty confused about the whole thing; because I thought we kind of had…I don’t know…Some kind of a relationship, however weak it may have been. I’m not sure how I should act when he gets back. Will it be the same as before he went on his little hiatus thing? I don’t know. Does he even like me? Or am I just one of those people who feels things that aren’t there?
Some other things about Neil which may aid you in your response:
Neil is kind of a misogynist, but he’ll shock you with a really tender, caring gesture every once in a while. He doesn’t think of himself as a very worthy or good person; He often talks about how he’s just a big moron, or an a-hole. He’s asked me several times why anyone would ever like him. He seems like there’s something inside of him that just makes him feel like an unworthy dirt bag or some such thing. He’s really sweet; you just have to know how to get it out of him. And seeing his sweet side, well, that’s like seeing the entire world covered in Christmas lights.
So I guess my questions here are: What do you think about this whole situation? Do you think it’s possible that I just imagined us actually having some kind of relationship? Should I just act the same way I did before he left, or what? I almost want to be a little cold to him, even though I’ll be really glad to have him back. I’m just a little frustrated with the whole thing. But I really like him and want to be with him, I just don’t know how to make it happen. We’ve been in this dumb escapade for almost a year now. I’m getting a little sick of it. How do I get Neil to make some kind of commitment? I’m not the most vocal person, I feel like it would be too hard for me to just be like “Dude, What the Eff?”
Thoughts…?