While he just innocently stare at you and continue whatever he's doing at the moment. And when he finally acknowledged it, he'll make you work for it, beg, or maybe drag him somewhere, and that'when he finally give you what you want.
#yogenjot
Flirting with him doesn't work the usual way, because he'll turn it into a word play, a jokes, or completely deflect it so smoothly you don't even realize it. But when he's in the mood to get back at you, you're the one who's gonna turn into a squirming mess