It was the end of sixth year.
Potter had been avoiding her, and good riddance. Ever since she’d threatened to go to the headmaster in fifth year she’d waited and watched for him to slip up. He didn’t do anything though. In fact, what Lily saw was James actually helping younger years with homework, keeping Sirius in line, and being more serious about his own studies. The more she watched him that year, the more she saw him change.
When they were both called up to the Headmaster’s office and told they would be Head Boy and Girl together, he simply shook her hand and said “Good job, Evans” and walked away. Lily watched him walk down the corridor and answer a second year asking for directions and just thought “Oh bugger…”