We've all seen the fics where Harry is dumped to another world from one McGuffin or another (the Veil, a ritual, the Room of Requirement, the Chamber -- you name it, it's been done), and we've seen fics where Dumbledore and the Order summon a hero from another world to save them... which is typically Harry.

But I don't think I've seen a fic where the two are used in tandem as part of the same plot.

Harry gets isekai'd to another world -- maybe it was a muggle Truck-kun, or a thestral-drawn carriage, or he slipped on a banana peel and went through the Veil, but regardless he had his arse kicked kicked into another world.

Dumbledore quickly works out what happened (even more hilariously if it were from a muggle method, like a CCTV camera seeing Harry say "aw, shit" before Truck-kun smashes into him and he vanishes or something)), and works out a way to drag him back within a few days or a week, tops.

The main issue is that there's a time differential: a week on Earth may be like ten years passing wherever Harry ended up.

Now, one possibility is that he returns looking his age e.g. twenties and thirties, or the other is that he returns at the same age (biologically) as he did when he left but has all the memories and experiences of that world's time-frame.

Either way, he did the typical isekai shit.

Now, the two routes:

One that he hated it. He was pressed into being a hero. He was pressed into doing all the dumb shit you'd expect, and he's just... done.

Dumbledore pulling him back was a gift from whatever deity exists, and he's freaking out his friends with how happy he is to be back from what was basically a death world.

Only, the people he left behind, included the cliche love interests? Yeah, they're looking for him and causing utter chaos -- especially when the yandere of the group ends up leaving tortured-to-death Death Eaters in her wake as she tries to get information.

The "Blood Knight" of the group? Yeah, she goes batshit crazy like Delta from Eminence in Shadow, and she's carving a bloody swath through through groups.

He's more scared of them than the Death Eaters!

The other route is that there were no "big evils" or anything else -- he just settled down, found love with a woman, married, and had a family.

Now that he's back on Earth, he's depressed he'll never see his wife and kid again... only for them to turn up as they traced what brought him back to Earth, much to his joy.

The conflicts would be that his wife has a very orange and blue mentality or different morals from living in another world, and that Harry is now a family man despite possibly looking like a teenager (which makes his son/daughter laugh their arse off as they're the same age now). His friends can't reconcile the Harry they knew from like a month ago to the new Harry in front of them who lived his life.

This is a bit rambly but it just popped into my head (blame the vodka).