James- he said it first. It was a couple days after your first kiss. Now he doesn't stop saying it
Sirius- You said it first. It was after a late night date and as he went to walk to his common room it slipped out. He didn't hesitate to say it back
Remus- you said it first. It was after a full moon and something went wrong and he got hurt a little. He was quiet for a second or two before he said it back and kissed you sweetly