It's been ten years since the Battle for Hogwarts, during that time Harry and Hermione both joined the Department of Mysteries as field agents and researchers. Harry specialized with spec ops and combat research. Hermione specialized in demolition and muggle tech integration. Most of the time they take latest technology from the muggles and find way to make it run on magic. With the research from the mundane's in regards to power armour Harry worked on a magical version. Using alchemy and science Hermione created a crystal power source the size of a fist and uses ambient energy to recharge. The armour is much more streamlined with unbreakable, lightweight and flight runes added throughout the frame. Blasting hex engraved on the fist to increase power to punches. Retractable blades charmed to be unbreakable and to stay sharp and lastly a shoulder mounted mini-gun that shoots pre-programmed spells.
While the wizarding world was experiencing peace the rest of the world was gearing for war. With oil prices rising all countries in the world has increased their military due to mounting tensions. Due to this the DOM initiated Project Arc. All knowledge both magical and mundane were to be copied, stored and secured. This means all books of magic spells, potions, wards, etc as well as blueprints on mundane vehicles, factories machines, medical formulas, weapons, armour and all related research were to be found, copied and put in expanded trunks and entrusted to their top agents who will go under stasis.
When Harry and Hermione were given the task to head the project they took it one step further. Expanded trunks with greenhouses of magical and mundane plants, multiple breeding pairs of all known animals and creatures excluding dragons. Precious metals gems and artifacts. And most important of all sperm and egg from most of the wizards and witches in Britain as well as several hundred from mundane. That took a lot of convincing and misdirection to get, as they created a wizarding version of a fertility clinic that used homunculus wombs to carry the foetus till birth allowing the parents to have multiple children. Harry emptied all the vaults he inherited adding books of dark magic from the Black vault, weather and earth magic from the Potter vault, books on necromancy from Peverell, research note of alchemy and an incomplete philosopher stone from Flamel and lastly the real philosopher's stone that Dumbledore said he destroyed as well as rare books in his vault and the entire contents for all death eater vaults through right of conquest. Several of their friends pitched in with copies of books and artifacts from their families. Then they raided public libraries, factories and army bases for anything of note.
The team consisted of Fred Weasley, Neville Longbottom, Daphne Greengrass, Luna Lovegood, Lily Moon, Susan Bones as well as Harry and Hermione. Each one is equipped with a reverse time turner that will put them and those within 100 meters out of phase for couple hundred years in real time while they only experience a few seconds. They managed to have it all done in a year. With the trunks shrunk and put in moleskin bags that the Arc team carry at all time they continued with their day to day lives. Harry and Hermione continued to adapt magic and technology. They made cars, bikes and VTOLS to run on the energy crystal.
And all was well till October 23 2077.
AN:
Quick notes on the time line. Battle of Hogwarts in this story is was on 2066. The use of homunculus for Invitro use is based on a fanfic I read a few months back. The reasons live dragons were not included was due to the fact that the individual reserves would be hard pressed to replace breeding pairs. Dragon eggs will be in their place. The mentioned books will play semi important roles in the future. The Magi armour is basically a cross between Warmachine from Iron Man 2 and Gypsy Danger from Pacific Rim. Think ZPM for crystal power source from stargate. Think semi futuristic vehicles like from Halo. also I do not own Harry Potter, Halo, SG1, Marvel, Pacific Rim and Fallout 4