Remus just stared at James for a long moment. True, Remus himself had made the attempt to ease relations with Severus. Sirius had exchanged jokes with the man. But, James Potter? He'd decided on the train at eleven years old he didn't like Severus and now had seemingly changed his mind in one dinner?
It must have been some dinner.
"I think you're actually the last one to admit that, Prongs" he teased, trying to lighten the mood just a little before Sirius had a coronary at the newer revelation Severus had been invited to dinner before they had as well. The fact the teasing was true and every single one of them in that room had conversed civilly with Severus before James only made his insistence on civility that much more amusing in Remus' mind.
"That's not really the point, though, seeing as none of the rest of us still hated him before this, is it?" The point was that James hadn't even considered coming to them, hadn't considered how Sirius, especially, would react to finding out he was second best to Severus. Remus was used to being the second consideration. Although, second to Severus was still mostly unbelievable and he wanted to ask what they had done with the real James Potter.
But, Sirius and James...
"Still, I agree with James. Harry would have been very happy for you. His family's happiness meant everything to him."