Lily said goodbye to her parents and boarded the Hogwarts Express. She saw many familiar faces saying goodbye to their parents, including Sirius and James being hugged and kissed by Mrs. Potter. She thought that was weird – what about Sirius’ mother?

Shrugging, she boarded the train and found Lupin in the Prefect’s compartment alone, looking much skinnier and worn out. She leaned over and gave him a big hug, saying “How was your Summer? Did you get head boy?”
“It was like most other summers, I suppose,” he said, and looked up to see Lily wearing a brand new badge. “Oh you got Head girl! Congratulations,” he said beaming. “I… didn’t get made Head boy though, no.”
“Hmm I wonder who-” she started, then her jaw fell open.

James Potter walked into the Prefect’s Compartment, showing them all his Head Boy badge.
“You? YOU!?” asked Lily loudly.
“Yes Evans, Surprised?” he asked, sitting next to her and putting his arm around her.
“Langlock,” she said, pointing her wand at him.
He mumbled loudly but could not form any words.
“Potter do not use this Head Boy for your own little ego power.”
He shook his head.