Time-traveling Mumscarian AU
Grian is the time-traveler from the future: he's supposed to just watch over certain past ages and figure out mysteries. These mysteries include but are not limited to; murder cold cases, cryptid sightings, and some immoral religious practices.
Scar is one of the cryptids that Grian investigated: he's just an immortal wizard(?) who is seen everywhere and nowhere at the same time, no one knows how but he also had a career in acting for a while before needing to go into hiding again.
And then there's Mumbo who is just a random guy: One time as Grian was about to travel to a different time Mumbo saw him got curious and so he waited years to see the mysterious man again. He does see Grian again and he stops him and they become quick friends.
This is more than likely a bit slow-burn with the pacing.
