Harper Vale disliked doing anything slowly if a faster version existed. She walked quickly, ate quickly, answered questions before people finished asking them and opened presents with the efficiency of someone trying to defeat wrapping paper before it could regroup. Her magic had developed the same habit. By the middle of first term, this had become a problem. Professor Ward placed a ceramic cup of water in front of each student during Making and Mending. A temperature strip lay beside it.

"Warm the water by five degrees."

Harper raised her hand. "Can we do ten?"

"No."

"Why?"

"Because the exercise says five."

"That feels arbitrary."

"It is extremely deliberate."

Jasper's first attempt produced no measurable change. His second managed one degree, and his third reached four. Ava achieved exactly five on her second try and allowed herself half a second of satisfaction before pretending she had expected it. Harper's cup steamed. Ward was beside her immediately. "Stop." Harper lowered her hands. The strip settled seventeen degrees above the starting temperature. She brightened. "That's quite good."

"It is twelve degrees beyond the instruction."

"But I controlled it."

Ward looked at the steam. "Did you?" The next attempt reached fourteen. Then eleven. Then nine. Harper became more frustrated with every improvement because none of them was five, and the frustration made the heat gather faster. Jasper could see it in her shoulders before the cup even changed.

"Stop," Ward said.

"I nearly had it."

"Stop first. Be annoyed second."

Harper folded her arms. Ward sat on the edge of the demonstration table. "What is the exercise?"

"Warm the water five degrees."

"That's the target. What are you practising?"

Harper frowned. Ward tapped the temperature strip. "Stopping at the amount you chose. Power you cannot stop is not extra power. It is missing control." Nobody laughed. Ward had not said it harshly, which made Harper look even less comfortable. She tried again. Six degrees. Harper groaned.

"Good," Ward said.

"It was wrong."

"By one. Yesterday you were wrong by twelve."

Harper stared at the cup. Jasper understood something about her then. Harper enjoyed appearing fearless, but she hated being visibly bad at things. Those were related problems, not identical ones. After class she kicked a pebble across Founders' Courtyard.

"Stupid water."

Jasper looked at her. "The water didn't do anything."

"Exactly."

Ava walked on Harper's other side. "You improved."

"Don't."

"I am attempting support."

"You're doing it badly."

Ava considered this. "Would you prefer dishonesty?" Harper sighed. They reached the western wall, where the sea below was rough beneath the afternoon wind. Harper rested her arms on the safe inner ledge and watched the waves.

"Do you think I would've been good at whatever the Deepwater student tried?"

Jasper felt a chill that had nothing to do with weather. "What?"

"Professor Elowen said they thought they could influence the sea. If it was about power..."

Ava shook her head. "We have no evidence that it was."

"I know. I'm asking."

Jasper remembered Ward's sentence.

"Maybe that's why it went wrong."

Harper looked at him.

"Power you can't stop," Jasper said.

She turned back to the ocean. "Maybe." That evening, Harper practised with a mug in Room Fourteen. Nobody had assigned homework. She borrowed Ava's temperature strip, sat at the desk and tried again. Eight degrees. Seven. Six. Then five. Harper stared at the result. Ava deliberately looked away.

"Don't say anything," Harper warned.

"I wasn't going to."

Jasper grinned.

"You either."

He raised both hands. Harper tried once more and hit five again. She leaned back. "Easy." Ava made a sound that might have been a laugh. Harper threw a sock at her.

For several minutes the room became a small war. Bag Bed suffered most of the casualties and ended the evening with three socks, one pillow and Jasper's Ancient Selari workbook on top of its existing collection. Later, after lights-out, Harper spoke from the dark.

"Jasper?"

"Yeah?"

"If that sea thing happens again, don't try to make it do anything."

Jasper opened his eyes. "I wasn't going to."

"Good."

There was a pause.

"Why?"

Harper shifted under her blanket. "Because I don't like things you can't stop." Jasper looked toward the faint rectangle of the western window.

"Okay."

The ocean moved normally below the cliff. He wished he could promise it would keep doing that. Harper's control problem began affecting things outside class in quieter ways. She shut drawers too hard when annoyed. Her bedside lamp brightened during arguments. Once, while trying to pull a book from under Bag Bed, she accidentally dragged two other objects with it and sent the west-stair pebble rolling under Jasper's bed.

"Your magic is dramatic," Jasper said.

"My magic has personality."

Ava retrieved the pebble. "Your magic has poor impulse control." Harper threw a pillow at her without magic, which Ava called an improvement. Professor Ward began giving Harper stopping exercises rather than stronger ones. She practised bringing moving objects to rest at exact marks and lowering shields smoothly instead of dropping them the instant a threat ended. Harper hated the work because nobody watching would describe it as impressive. That was partly why it mattered.

Jasper saw the first real change during a corridor accident. A younger visitor on Parent Weekend dropped a glass bottle. Harper reacted before anyone else, catching it with a burst of force half a metre above the floor. The bottle stopped. For an instant Jasper expected it to shoot upward or slam into the wall. Instead Harper held it there, breathing carefully, then lowered it into her hand. The child's mother thanked her. Harper looked pleased for the rest of the afternoon but did not mention the temperature exercise once.

Harper could not do anything slowly if there was a faster option. This included walking. Eating. Opening presents. Answering questions she had only half heard. And magic. By the middle of first term, this had become a problem. Professor Ward demonstrated the exercise with a cup of water. Control, Jasper realised, was beginning to become useful before it became visible. He knew enough now not to try.