Fenrir actually paused when he heard Lupin's mate start talking and if he could have laughed he would have. She thought he was Lupin? Clearly she had never seen her mate when he was the wolf or she'd never have made that mistake.
He howled and redoubled his efforts at the door, amusement mixing with his irritation. If she thought he was Lupin then how was she explaining the other wolf with him? And she probably thought he was doing this mindlessly. More fool her.
The door he was crashing into creaked alarmingly at his latest attack and he snarled triumphantly. Two more blows and the door splintered and he crashed through, smashing through the chair that had been wedged against the door. He looked around just in time to see Lupin's mate disappear out of the window. He loped over and leaned out, snarling savagely in what would have been swearing if he was human as he saw her running towards the village.
He turned and padded over to Natasha, licking her muzzle to calm himself. One prey had escaped but Lupin's mate hadn't been his only target tonight. He raised his head and howled then loped out of the room. Their next stop would be the warded area. He intended to let the other werewolves see true freedom and power. See that they didn't have to kowtow to the Umbridge woman, be weak and whining pups.