Coward
He had heard Potter's voice say it the first time he entered the Headmaster's office and let his gaze caress everything in there possessively.
Coward!
He had heard it when he signed the decree making the new Muggle Studies obligatory to all.
Coward!
It had been ringing in his ears as he caught the three Gryffindors stealing the sword.
Coward!
He reinforced the Disillusionment Charm and heard it again as he watched two battered students carrying a third, barely conscious one, three times down the hallway, and then disappearing.
Coward!
But he didn't go after. And the ringing died down.