Lily and Remus were running, once again, to the screaming. It was coming from people standing around. It was James and Severus, fighting. They had arrived too late, and whilst Severus shouted “Furnunculus” at James, he had levitated him up in the air and was bouncing around upside down.
“James let him DOWN!” Lily yelled.
“No – he… No!” James said.
“James, what are you doing?” Remus asked. “You know this will have to be reported, don’t you?”
When they had gone to se Professor Dumbledore last year, he had warned them to let him know as soon as any fighting broke out.

“Severus are you okay?” Lily said, after James let him fall on his head, once again. She was touching his face, looking over him to make sure he was okay. Sirius was howling with laughter at the sight of James covered in boils.
Remus offered Severus his hand, trying to help him up, but he got up on his own and spat “I don’t need a Mudblood or a moon freak helping me,” and walked away.
If Remus’ reflects hadn’t been expecting retaliation, he wouldn’t have been able to grab James as he tried running after Severus.