she's playing it cool but she's lying (better than I do)
His eyes widen and he watches James bring three of his fingers—fingers that are still glistening, still coated with Regulus—up to press down on Lily’s plush bottom lip. She accepts them, and she moans as she seals her lips around the digits and hollows her cheeks slightly, sucking.
Regulus would say that it’s the hottest thing he’s ever seen if it wasn’t for the way that only a split second later, Lily has her hand wrapped around the bottom of Regulus jaw—pressing on the hinges in a command for him to open. She tugs him closer and spits right into Regulus’ open mouth—his own taste being delivered onto his tongue.
OR
Lily decides that the three of them should play twenty-one questions—with veritaserum. Obviously, this leads to some interesting realizations.