This sort of reminds me of a much sadder story, where a kid was forced to work as an assasin, fell in love with someone else - I think a dancer, but I'm not sure? - and occasionally watching them was all the comfort they had. Eventually they got her as a mark, refused to do it, and got executed by their employer for it.
It was a oneshot or very short like this one; does anyone by chance know that story? I've lost the bookmark ages ago x.x