You've always been happy being a Gryffindor, everyone liked you. You were dating James, Remus and Sirius, in secret, of course. They started finding your comportment weird. You were always tired, and hanging with a weird group of friends.

Regulus went to talk to Remus, James and Sirius, telling them that he found you using illicit stuff with your new group of friends, it was weird since you'd always been innocent

Remus: She what...? James: She wouldn't! She's our girl..