I have about 1,600 hours into Skyrim, across 16 characters. No mods (360).
All but two of them are "internal-world consistent". This means that no single piece of unique equipment, or home, or spouse, or child, is used twice. All fourteen characters effectively 'live in the same world', in a sense. Two weren't possible to do this, because of finishing the Civil War an alternate way, and another completing the 'evil' ending for the Vampire DLC.
For test purposes, I decided with one of my characters to exploit the OI book leveling glitch, and run her up to level 81 right after creating her. The point was that she had a looong, mysterious history of adventuring unknown to her or even to me, the player. To reflect this amnesia I didn't even spend most of her skill points. I played her just enough to marry Mjoll, who had her move in.
I decided that her entire story actually took place in the deep past, and at the end of said career, something 'off-camera' threw her a thousand years forward in time, and into the 'present-day' world of Skyrim.
That's one of the ESO characters I'm going to play.