The smirk on his face was immediately overpowered by a real smile.
"Oi, it's lovely to see those bright eyes looking my way again." said James. Lily gave a hearty laugh and began gathering the potion ingredients. James followed her lead. She acted perfectly friendly while she started the potion, waiting for Professor Slughorn to sit down and distract himself. She used the time to think through all her options, and decide exactly what to say. Finally Slughorn sat down to read.
"Chop these," Lily said as she placed a handful of frog toes in front of James. Then she lowered her voice to a whisper.
"Why are they talking about expelling you?" she asked without looking at him. There was a pause before the answer came; and when it did, it was carefully controlled.
"Who's talking about expelling me?"
"I didn't see who, I just heard some voices."
"What did you hear?"
"Nothing informative. Why isn't Severus in class today?" This time she glanced at his face. She expected to see a hint of pride, or else guilt. What she found was much closer to annoyance.
"He had an accident with the Womping Willow last night. I simply found him and brought him in." He was trying to sound as if that were the whole story. Lily knew better. She had seen him lie plenty of times before.
"If that's true, why should you be expelled?" she asked.
"I shouldn't be!" he said, a little too loudly. "They think I did something to him and I didn't! He would have died if I hadn't been there to save him!"
Lily looked around to see if anyone had heard him. None of the students were looking their way except for Sirius. She wasn't worried about him. He undoubtedly knew the truth already, and was powerless to stop James from telling her anything at this moment. But Slughorn was right in front of them. He was still looking down at his book, but Lily sensed that he wasn't reading it. She decided to end the discussion for now.
"Stir this clockwise seven times while I put these ingredients away," she told James. He obeyed, and they spoke only of the potion until the very end of class.
They were packing their things. Slughorn was standing again, observing all the potions. There was still one thing she had to say to James... one reaction she had to see. She knew that Slughorn might still be listening, so she chose her words carefully.
"I don't know what you could have done to him that would be too horrible for you to be proud of. I suppose I'll know the truth soon enough, when Severus returns from the Hospital Wing."
Lily could think of nothing else while she walked through the castle to the History of Magic classroom. She sat in the very back, her mind racing while Professor Binns began his lecture. He refused to notice the students nodding off, one by one; he continued his dreary monologue without pause.
Lily was lost in thought. James was certainly not proud of whatever had happened. So he either did something to Snape that went horribly wrong, or else he really was innocent. But if he were telling the truth, why did he seem so nervous when she mentioned speaking to Severus? He clearly thought that Severus might tell her something he didn't want her to hear.
Then something occurred to her.
Wouldn't Severus be embarrassed if James's story were true? An accident with the Womping Willow, and he would have died if James Potter hadn't been there to save him... He would be mortified! Could he have lied to Madam Pomfrey and the rest of the staff? Would he lie to Lily? Maybe he decided to use this opportunity to get back at James for all the cruel things he had done to him in the past. It wouldn't be difficult at all to convince the school that Potter had done something to him. What an ungrateful thing to do to someone who had just saved your life, Lily thought.
She didn't want to think that her old friend was capable of such a despicable act. And yet... If Severus weren't the despicable one, then it was surely James. Which one was it? She was torn. She had seen them be incredibly mean to each other, but she had always believed them both to be good wizards at heart. She was accustomed to sticking up for Severus and blaming everything on James, but this was different. One of them had gone too far.
It was hard for her to admit it to herself, but despite his arrogance and everything else she hated about him... she found herself hoping that James had been telling the truth.