James using his Invisibility Cloak to hide all the chocolate he bought for Remus.
Sirius stealing McGonagall's notes to try to see if there's anything on how to turn into an Animagus (and getting detention for weeks).
Peter purposely tripping over other students to let way for Remus when's it's almost the full moon and he's really tired.
Remus thinking about this when he's casting a Patronus.