One of the characters in my (would be) game becomes deaf from a car accident early on in his life. Because of the circumstances surrounding the car crash, he refuses to use his hearing aid for anything outside school.
So when he talks to people outside of school, he relies heavily on lip reading, to the point where some people don't even realize he's deaf - he keeps the fact that he's deaf a secret.
The rare times his lip reading skills don't "save" him, such as when someone called out his name when he was looking the other way, is just blamed on social awkwardness, something along those lines.
Cue the question above: how well would a deaf person be able to read lips? I know there are certain factors that affect how much you understand (I heard lip readers hate people with beards and moustaches), but could it be so good that someone might not even notice that the person they're talking to is deaf, unless they notice how fixated the person is on their lips?