Dennis looked up at the cheerful voice and there was a girl. A girl standing over him and smiling. "Hi...?" He didn't mean for it to sound like a question but he was a bit confused. He wasn't used to people randomly approaching him, he was kind of excited though. His heart was beating just a bit faster.
Someone was talking to him!
Unsolicited.
And he felt horrible because he thought she was a Gryffindor but he had no idea what her name was. He used to know everybody's name, because of Colin.