Severus came back with two glasses of pumpkin juice at the end, he placed one in front of Charity, frowning down at it: "I hope this will meet your tastes as well... the punch had something off I wouldn't trust..." He was a potion master after all. And he couldn't help but think one of those shady ex students had something in mind. He didn't like that, this was Hogwarts, his students were supposed to be safe, but he figured Dumbledore was smarter than letting those people in without some sort of precautions. Some people really didn't know composure.
"I am afraid I'm not so much of an expert in regards of parties... does it seem off to you?" he asked, letting his eyes roam the hall, many people he knew, he was supposed to greet, but hell, he didn't feel like it. "Should we go and empty the punch bowl? We are in charge after all..." he muttered with a sigh, he had taken a sample vial to find out what had been added, maybe it was going to be useless, but Snape wasn't one to be caught by surprise.