He was killing Cass. Bloodily, painfully killing Cass. As soon as he stopped blushing because right now he knew his cheeks were bright red.
Unfortunately Cass had also put them in the position where it was lie or tell the truth, besides Harry knew Cass would push the threesome if he thought they were together.
"We're not together Cass." Harry said as he dropped his hand from Pansy's shoulder. "Pansy was worried about Polly's safety and Malfoy asked me to move in and play bodyguard."
He felt a bit relieved after telling the truth, especially since he knew he wouldn't be able to particapate in a threesome for the sole reason of keeping Cass from finding out their secret, and since the secret was him living here and that was out it made sense to tell the rest of it. "I've been living in a room on the second floor."