You cannot afford to risk asking him our while supervising him. Whether he says yes or no, it can and likely will blow up in your face. That said, I met my husband at work. We were equals, and working in different departments, so we didn’t have the whole quid quo pro harassment issue to worry about, and we both went to our supervisors and asked permission before we went on our first date, but it still did create problems for other people and a perception of conflict of interest. Your best bet is to wait until he is no longer working for you, orchestrate a transfer for him to start reporting to someone else, or use some other creative method of avoiding sabotaging your career in the pursuit of love. It sounds like at this point, you don’t know if the feelings are mutual. Be aware that some of what you see in him may be part of his need to impress his Supervisor rather than his genuine self, but then again, he could actually be everything you dream he is. Play this one smart… If it is really meant to be, he’ll still be around after you aren’t supervising him anymore.