They've returned to Hogwarts after Christmas. Lily sees Severus and pounces on him, hugging him tightly.
He winces under the pressure, but tries not to show it. Lily notices.
She rolls up his sleeve to discover a shoddily bandaged gash in his arm, bleeding profusely.
She arches an eyebrow and he shakes his head. No hospital wing then.
They make their way to the bathroom, and Lily pulls out her secret stash of medical equipment and begins fixing him up.
He sits stoically as her eyes glisten and she tries to keep her hands steady.
It's not the first time.