Axel wasn't saying no. If he said no, Luke would probably try to get him to say yes a few more times but would have ultimately left him alone. Now, of course, there was no way Axel could know that. The only insight he had really given of his character was his quick draw on the trigger and a jealousy issue. He had more issues than that, of course, why wouldn't he, but Axel might not do much better.

Who in his life had ever told him that he would kill to protect him? Who obviously meant it? No one.

"I'm tired of being alone. I thought you might understand what that's like." It wasn't a remark meant to disparage but, yeah, it came off as a little snippy. Even if Luke's expression was fairly even. "Jesus fucking Christ dude. I don't even know, okay? I like you I guess."