Coworker checks me out but is rude?

he always seems annoyed by me and my questions (he is the helpdesk guy), but he also always laughs at the things i say and continuously checks me out or kind of looks at me from a distance and/or blushes when i speak with him. one day, he couldnt help me locate stapes so i was like, ok forget it. an hour later, he showed up at my desk with a box he had poached from someone else. sometimes, he is very nice but he still looks uncomfortable wen i say thank you or anything. ever since ive known him, he can't say you're wecome or sorry. i hate it and then on top of that he's always looking at me. i dont know how to deal with his rudeness/checking me out? it makes me uneasy. i do think he's attractive but dont know if he's seeing someone or what his scenario is.