Wow! That reminds me of something something that happened on my main Oblivion (Elder Scrolls IV) save once. It's a long read but I think it's worth it.
So in Oblivion there's an item called the Skull of Corruption, which you can use to clone NPCs. Using a glitch, you can use it to permanently clone yourself.
When I discovered this glitch online, I had already played Oblivion to exhaustion. My character, Nickies, a Breton battlemage, was nigh-invulnerable, and had spells that could one hit Minotaurs. It was pretty crazy, but it got boring fast. I decided the only challenge left was to fight a version of myself, a permanent clone, a "Nickies Black," if you will.
So I did the glitch, purposefully not wearing my best gear as to make sure I can still win, but couldn't immediately kill the clone because his (my) healing spells were too potent. So, I left and returned, to see what would happen to him.
He had changed his equipment loadout to that of my own, real character's, including all my OP shit. Now I actually couldn't kill him...
Not only that, but he started upchucking a creepy mix of faction dialogue I haven't heard before, like "I'm sworn to die, are you?" and "The training of thousands has passed through me!"
Sometimes he would use my invisibility spells and flee, and I'd have to find him again. One time I found an entire town murdered, with him nearby. I even got bounties when I swore I didn't commit any crimes. Once I led him over a bayou to an underwater DLC home I had, and he equipped my waterwalking boots to easily keep pace - then, when I fled underwater, he swam under with me despite wearing said boots!
Other oddities include his Luck seemingly being higher for everything he did compared to my own, and being able to summon two things at once (which was actually IMPOSSIBLE in Oblivion).
Eventually our endless fight led into the Imperial City, the capital. (Continued in comment)
