Louis Weasley (and Minerva McGonagall?)
Originally Louis had thought about not coming to the party; what with Minerva suddenly being incapable of speaking in anything but riddles. However, she had still wanted to go and there was also the fact he too had already accepted the invitation. Plus he wanted to show that even though it was still weird for him that, at the very least, he was okay with the idea of his mum and Mr Malfoy being together. It was definitely a whole lot easier to deal with than your dad being eight years old that's for sure.
Louis had to admit that the place was looking pretty nice. Whilst he was admiring the decorations as he and Minerva, because he'd been roped in... okay, he was actually pretty happy to go to the party with Minerva anyway and he'd been the one to offer himself as a translator of sorts for her. Anyway, whilst he was admiring the decorations that he spotted Draco and figured he must be there greeting people as they came in; otherwise it was a bit odd just standing around at your own party like that. He tapped Minerva on the shoulder and pointing over at Draco told her that he was going to go say hi.
"Uh hello, Mr Malfoy," he greeted, after having walked over. Okay, it was definitely still weird to talk to the guy who was with your mum and wasn't actually your dad.