"Ah," said Lupin. He considered Harry for a moment. "Why don't you come in? I've just taken delivery of a grindylow for our next lesson." 

"A what?" said Harry. 

"Nasty littler bugger." Answered Amelia.

They followed Lupin into his office. In the corner stood a very large tank of water. A sickly green creature with sharp little horns had its face pressed against the glass, pulling faces and flexing its long, spindly fingers.

"Water demon," said Lupin, surveying the grindylow thoughtfully. "We shouldn't have much difficulty with him, not after the kappas. The trick is to break his grip. You notice the abnormally long fingers? Strong, but very brittle."

The grindylow bared its green teeth and then buried itself in a tangle of weeds in a corner.

"Like an alligator's jaw." hummed Amelia.

"Cup of tea?" Lupin said, looking around for his kettle. "I was just thinking of making one."

"All right," said Harry awkwardly. Amelia gave small nod not sure what to say.

Lupin tapped the kettle with his wand and a blast of steam issued suddenly from the spout.

"Sit down," said Lupin, taking the lid off a dusty tin. "I've only got teabags, I'm afraid -- but I daresay you've had enough of tea leaves?"

Harry looked at him. Lupin's eyes were twinkling. "How did you know about that?" Harry asked.

"Professor McGonagall told me," said Lupin, passing Harry a chipped mug of tea. "You're not worried, are you?"

"No," said Harry.

He thought for a moment of telling Lupin about the dog he'd seen in Magnolia Crescent but decided not to. He didn't want Lupin to think he