Fingers in mouth during sex...

So when me and my partner are having sex he chokes me and all the rest of it which I love. But he always puts his 2 fingers in my mouth and makes me deep throat them which turns him on but then he leaves them in there. Sounds stupid but what do I do with them? Do I just like suck them and stuff? Idk, I don't mind him doing it but I've always just wondered haha.