Lily knew she wouldn't really be able to hold James back, but she sighed all the same as he pushed her away and walked towards Sirius. She stood up when she saw him get closer, worried that he might actually hit him. If he did that, she felt like that would knock Sirius out for good.
Her eyes grew wide as he yelled at Sirius and they turned to look at Sirius when he responded. He doesn't remember anything she thought. That was natural in a hang over, but she was almost certain he had more than just that.
As James began to yell louder she walked towards them and then it happened. Before she knew it, James had his friend pushed against the wall, his arm raised to hit him. "James, NO!" Lily rushed over, grabbing his arm with both of hers. "James, please, look at him! He's not well and he doesn't remember anything! Calm down, don't do this!" She could almost hang off of his arm without having it budge and she was close to doing just that. Instead, she kept her hand on his chest and moved around him so she was within his eyesight. She couldn't exactly step between the two, but she did the best she could. She hoped he wouldn't hit her, that his anger was blinded by that. It was a ruthless thing to do, but she knew Sirius wouldn't survive a hit James would throw his way.
"C'mon, sit down. Let Sirius at least explain himself. Remus would do the same for him, I'm sure of it."