Harry had and didn't appreciate it. He didn't know anything about poltergeists. For some reason neither they nor ghosts had been mentioned in any detail in any of the Trimble books. Perhaps the late Headmaster Trimble hadn't thought ghosts should be attacked?
So Harry had to guess... Fire? No. Water? No. That cutter, Diviso, he'd been working on? No.
"Fulmenifer." Harry jabbed his wand.
The lightning was a pitiful bolt, but it hit true. Harry had to wait for the flash of light to stop adding spots to his vision. He blinked a lot. This was another drawback to the lightning-bearer.
However, it worked. Peeves was now a bunch of muck splattered on a wall, like an ooze.
"Potty, Potty, my new best friend. You bring the best Yule gifts..." A much dimmer-seeming poltergeist floated out of the wall, through the ooze that had once been part of his...being. He was laughing, but his voice was thicker... In pain?
Harry was going to have to make a note in his book. The lightning-bearer could hurt a poltergeist.
"Truce," Harry said.
"What is a truce?"
"You leave me alone and I'll leave you alone."
Peeves looked horrified. "Never. Zappy-zappy is my favorite friend, Potty-Potty."
The dimmed poltergeist flew through a door and disappeared.
What a strange entity. Harry had almost killed it and it pretended to like lightning just to be contrary. Like Harry's aunt pretending to like chocolate biscuits just because Mrs. Wangle in Number Eleven Privet Drive liked to serve them. Petunia Dursley was actually allergic to chocolate which might explain why she was so sour.
Harry opened the door that Peeves had flown through and looked inside. It wasn't a classroom. It wasn't much of anything but empty space. There were more doors off the room, though. Harry found three smaller rooms attached, one a water closet.
An idea began to form in his head.
The dust here suggested this set of rooms wasn't used often. It had a restroom. One of the small rooms could be a bedroom maybe. Harry was no stranger to doing without a shower, but if he got a bucket he could still wash himself. That would give him someplace to hide out for the summer. No more Dursleys.
Harry spent the next hour looking through the rest of the floor. It really was disused, this whole section.
He returned every remaining day of the holiday break.
By the time the Hogwarts Express returned the students to the school, Harry had begun to fill his little area with things of value. A chair that he had mended with a reparo, a cot he'd found in a closet (and why had there been a cot in a closet?), boxes that would work in place of drawers and shelves.
Harry greeted Seamus, Dean, and Neville when they stumbled into the common room. Ron was napping again. He said hello to Hermione and a few of the other girls.
They all disappeared to their rooms. Neville took a seat in front of the fire. The shy boy who rarely spoke was smiling that day so Harry spent more time trying to become his friend.
It was rare, and pleasant, to see Neville so happy.
"How were your holidays, Neville?" Harry asked.
The happiness waned. "Good."
The boy couldn't lie. Harry could, of course, and he could tell when others were. Lots of odd skills that the Dursley family were useful for honing.
"But you're grateful to be back?"
That smile returned as bright as the sun. "Oh, yes."
Neville was another who thought better of Hogwarts than his own home. Harry, at least, wasn't alone in that. Sadly enough.
Harry's friend had grown up knowing magical things, though.
"I had a question," Harry said.
"Oh?"
"About lightning, electricity..."
"Err, I don't know much about it. Sorry." Downtrodden Neville was a sad thing to hear or see.
"No worries, mate. I was just wondering if lightning had an effect on ghosts..."
"Ghosts?"
"Well, yes." He wasn't going to admit zapping Peeves – or how much Peeves seemed to enjoy it. Peeves had sought Harry out twice before the holiday ended and pestered Harry to point where Peeves got himself zapped. It was getting irritating.
"Well, Gran did give me some books for New Year's. Maybe... Yes, there was one volume she insisted I read first. On things an Auror had to know..."
"And what's an Auror?"
"They put evil wizards in prison."
Police, Harry thought. Magical police.
"What did your book say?"
"Yes. Right. Well, it mentioned negotiating with ghosts for information. It said that ghosts did like certain things and would sometimes trade information for a gift. Strong smells, like rotten food. The sound of wailing. And lightning, especially lightning storms. Didn't say why."
"I wonder if that's why there's no electricity here. Don't want ghosts zapping themselves all the time?"
The idea made Harry smile. Ghosts as addicts to electricity...
"I could ask..."
Neville was so desperate to help. Like Harry had been, like Hermione still was.
"Just curiosity, mate. Let's get to the Spring Term Feast, shall we?"
"Can I dump my things first? I'm warmer now."
"I'll wait," Harry said.