James: He knows it becasue the way you speak about him with your friends.
Sirius: He knows it by the way you hug him and Kiss him.
Remus: He knows it by the way you hols his hand when you walk together.
Lucius: He knowsit by the way you cuddle in the couch in the slytherin common room.
Severus: He knows it because you Always smile when someone talks about him or when he is around you.
Tom: he knowsit by the way you kiss him and by the way you talk about him.
Reguluq: He knows it by the way you laugh when he's around you.