Sirius moves in – or rather Sirius has already moved in all his stuff in the years beforehand and now he just stops leaving. Harry already sleeps with James (it's such a bad habit, he's trying to stop) so they have to expand the bed to fit Sirius and Remus.

Remus has not said why he came over but he had a broken arm and was shaky enough that Harry followed him around for a while at the start.

Older Sirius has to leave because he has an adult job, but stays until all the other boys recover enough to be running around the backyard screaming excitedly about building a fort in the forest to camp in, before very reluctantly making his way out.

Sirius grabs a hold of his older self before the man leaves and they have a talk in another room. Sirius comes out looking…happy. Not a nice kind of happy either, more like Bellatrix – and Harry hates himself for thinking that but there's nothing else to compare it to. He's never seen that expression on Sirius before.

Sirius goes right back to chasing after Prongs for a ride but Harry makes a mental note to ask him later. Not that Harry would stop him but…

A few days pass and the teenagers build an entire mini castle in the backyard because Remus is a king and he will have his throne. They put a pool in and Sirius conjures a shark because sharks are cool but the pool is too small so James gives it legs because he feels bad when it looks cramped.

Harry's grandparents seem fine with it so Harry just makes sure to occasionally step in and herd the shark away from the edge of the wards so it doesn't get loose. That thing running full tilt at a muggle would not end well.

Apparently they miss a summons from Voldemort because Tom shows up but then he sees the castle and the Marauders loudly heckle him from a squat tower.

Three hours later the castle is destroyed and it's turned into guerrilla warfare in the forest around Potter Manor. James is flagging because he's still tired from the house draining his magic during the ritual, but Remus is soft with him and Sirius and Tom are distracted with maiming each other.

"They got distracted," Harry says as he watches from his seat on a particularly large piece of rubble while Voldemort walks up, arms crossed.

"What are the teams?" Voldemort muses.

"Free for all," Harry sighs.

"Black has impressive raw power, pity he's staying away from Dark spells."

"I'm surprised Tom is too," Harry admits. "He's strong enough, backed by you -and whatever he's done in the background to get his own power I'm sure- that it's strange he's still being…nice."

Voldemort continues to watch the boys for a long moment. "He has so much. More than he thought he ever would. He's still ambitious but no longer…ravenous."

Harry looks up at Voldemort standing above him and then turns back to his dad, Sirius and Remus, his grandparents feeding food scraps to the legged-shark.

"Yeah," Harry admits. "Yeah, I get it."

James takes a seat in Voldemort's throne chair while the man is shuffling through his paperwork and picks up a nearby book of dark green snake skin.

"Did the author have a stroke writing it?" James laughs, casually flipping through pages. "It's like fake writing - it's just scribbles!"

"It's Parselscript," Tom answers.

"What snake needs to write?" James scoffs.

"The wizards do, obviously," Tom's naps and snatches the book away before James breaks it with his careless handling. "It's a precious tome."

"Read it to me then," James huffs.

"You don't know Parseltongue."

"Read it in human," James points out.

Harry moves around to peek around Tom's shoulder.

"Does it work on writing too?" Tom asks Harry.

Harry tilts his head to the side. "I – uh, yes? What's it meant to look like?"

"Squigglies," James answers.

"Elongated English for me," Harry admits.

"The writing is a bit stretched," Tom explains. "That's not a part of Parselscript, that's bad penmanship."

James and Harry get given a thick packet of information they'll need to know for later and then Voldemort takes off and Tom leaves to study his own ominous self-lead research.

James reads half a page and then realises he knows it all anyway, so he runs off while Harry sits in the library, stressing over why he cares about these people and their companies – he's not the one making deals with them after all.

Harry gives up, he just follows James' lead anyway, and wanders around the Dark Lord's manor trying to find James. He finds him on the roof, James surveying his playground.

Harry and James make a slide winding around the Dark Lord's manor, snake themed of course. It's essentially a giant basilisk, with covered parts of skin or bone, but most is clear, uncovered glass so you can feel the wind in your hair and see just how high up you are.

James is lying back on a broom, keeping it held still with his knees as he draws runes into the underside of the glass, inventing a speed boost rune chain. He then glamours over it so the glass becomes pristine again and the runes can't be seen. He thinks a moment and adds cool colours because it's more fun if you can see it coming as you slide down.

Harry is sitting inside one of the covered parts, charming the walls to be pitch black, with colours in the 'far distance', meant to be rushing closer as you slide further down for a little scare.

They both do a hard double take at one point when they each realise Voldemort is sitting outside on the lawn sipping tea with several other people chatting over the delicate looking table and chairs.

Voldemort doesn't stop them though so…that's basically permission to mess with the entire building.

James ends up needing to teach Harry a crash course in runes and sends his son off to replicate some sections. Meanwhile, James lies on his stomach in a warding circle for an hour and a half, holding his wand like a quill and scribbling down runes he only erases right after.

The north corner is a mess of circular reasoning that James is too mentally exhausted to redraw properly, and there's one rune at the south-east anchoring everything on the east side and it's definitely overloaded but James doesn't know how to fix that because that's seventh year shit.

James groans and ends up standing, marching across the lawn and coming to a stop near Voldemort. "Do you know runes?"

"Which kind of runes are you talking about?" Voldemort offers, only because there are people watching.

"I'm trying to make a forceful apparition, adjusted for a certain height clearance," James explains.

A Korean woman sets her teacup down and peer across the grass to James' dirt circle. "What power stone are you using?"

"Well that's the thing," James sighs. "I don't have one, so I was thinking to drain magic from the person being apparated to power everything."

"I see your problem," the Korean woman hums. "Because that kind of ward doesn't exist."

James is speechless because he just spent an hour and a half-

Voldemort stands gracefully and gestures for James to show the way. "I would hate to waste all your hard work."

James, still incredulous that he wasted all that time, stumbles back across the yard. Harry coasts down on a broom and hops off, tentatively following behind the group of adults – who have also decided to join in on the fun.

Harry slips around and leans into James. "What are you doing?"

"Cheating," James admits. "You think I could bring my homework next time?"

They lure an unsuspecting Tom up and shove him down the slide. He apparates out before he even hits the first bend.

.

A/N: It's basically a Mario Kart track.