Knocking before entering a room? None of them really give MC a choice in the matter.
Pierrot, the lovesick puppy he is just barges in when he gets the urge to see his beloved. He doesn't like closed doors keeping you away from him.
Harlequin knows it's polite to knock before entering. But he prefers to sneak in as quietly as possible, waiting for you to be startled at his sudden presence.
Ticket Taker is probably the only one who actually knocks before entering. He doesn't wait for a "come in" but he at least is courteous enough to let you know he's there.
Doctor doesn't knock. If he needs to find you for some reason, he will. Knocking is an unnecessary extra step.
Jester likes to announce himself with tapping his claws against the door as he calls a random pet name. He never calls you by your real name. He's not doing it to be polite. His tapping is a way to lure the little creature out of hiding. His pet names lets you know he wants you specifically.














