Kyle entered the Great Hall, shoving the last book into his bag. He glanced around and spotted Siobhan. She was rubbing her eyes. He gave her a nod in greeting, then took his seat at the Slytherin table. Kyle ate quickly wanting to make sure he and Siobhan could get good seats. Part of their act had to be being close during DADA. Then making a huge scene after the class ended. He hoped they'd have a reason to make pairs. Or even better, if Snape had them break up into larger groups. Then Kyle could realistically know about the mudblood girl. 

It is a sign of how Kyle was raised that he didn't even realize that he called her a mudblood. To him the word was as common as muggle, and more common than muggle-born. Only a distant part of him completely realized the implication of the word. 

As soon as Kyle was done eating he crossed the great divide of the hall and joined Siobhan at her table. "You ready?" He grinned at her. He was just as excited as she was. He resisted giving any of the Gryffindors a friendly nod, couldn't let them think he was too nice.