The ultimate BBEG, ideas and thoughts please

[Setharious]

So, I have been running my first campaign for about a year now for 2-4 players. They have all been having a great time slowly getting stronger to fight Tarrur (I'm not great at names) who is an ancient black dragon. Since this was my first time DMing, I sadly did not immediately give him the backstory and such that he needs. 'Evil dragon is evil' was basically all I had. Lately, I have been having some, strange ideas, and I didn't know if anyone else has ever tried this.
The concept here, is that Tarrur is actually a character from a different adventuring party, and a different campaign all together. They used to be a wizard, but used true polymorph repeatedly to become a black dragon, and aged the hard way to become ancient. During their long lifespan they noticed odd things, such as hearing of barbarians to the north, going south, and running into those same barbarians. Or being defeated by much weaker people than himself for no obviously reason. Eventually, they began to worry that their life was not under their own control. That someone or something else was pulling the strings, but for many thousands of years they looked for proof and couldn't find it. Whether they weren't strong enough, or not talented enough is unknown to him. All he knows is something is out there and he needs help.
Seeing no other option, Tarrur began jumping from plane to plane, becoming the BBEG of many different worlds, looking to find adventurers who could outdo him in every way. Adventurers who were smart, stronger, and were also worried about their lives being beyond their control. Tarrur would use illusions to convey their feelings to the players, like putting the party into a town where they would die every day but wake up perfectly fine, reliving the same exact day. A groundhog day situation. Really try to show the players their life is out of their control, and the party never knows who is pulling the strings.
When Tarrur gets defeated, he will use the last remaining amount of his life force to inscribe symbols on each of the party members, which will carry between every character my players make with me, regardless of campaign, that will give them some skills from their previous lives and attempt to draw the party to one another no matter how many years of lifetimes they may see.
Tarrur, and this whole campaign, is turning into an introduction of the ultimate BBEG. Me. The DM. This is where I need help. How can the players beat the DM? I don't want it to simply be 'DM throws puzzles at players, the players solve them, and the DM quits' though that could certainly be a part of it. I want there to be high level meta gaming, possibly some things needing to be learned or obtained through multiple campaigns to even consider challenging the DM.
A thought I have had, is to make the DM quit by not playing his game. If you sit down in one spot not to move the DM could get bored or try to force something to happen, only for the character to ignore that too even at the cost of their own life. Do You have any other ideas on how to 'fight' the DM? Does this sound like a good idea at all? Any thoughts or advice are welcome and encouraged! Thank you.

Edit: Maybe a way to view this is not the players vs the DM, but instead fighting a DM like entity who pulls strings in the background, not nullifying player decisions but taking away control occasionally. Sometimes this DM like entity does it to be helpful, sometimes they are in a bad mood and try to 'rocks fall' someone, so the players decide they don't want this God above Gods to mess with their lives anymore and take them on. More similar to say... superman vs mxyzptlk. A level of meta gaming required, but not exclusively.

[Unoriginal]

The DM can't be beaten. Only way to stop them is to stop playing.

Also why is the DM the BBEG? Without the DM, nothing happens in the world.

Honestly it doesn't seems very fun to go all meta "ahaha the setting's characters are just the DM's toys and you have to beat the DM".

In the old D&D cartoon, the Dungeon Master was a powerful but not omnipotent entity, and any power he used had consequences. He was also helping the PCs, not hindering them.

[Avonar]

I think it sounds just too meta. The moment you introduct the DM and the players as actual in-game entities, you rob the characters of everything. They aren't characters anymore, they're just chess pieces. The players become the characters, and not everyone wants to play themself. It's not impossible for this to work, but I imagine it being very hard, and something you can only attempt with a very specific group. It's an idea that could put a lot of people off, and if one player doesn't like the concept then it will just fall apart.

[Setharious]

In the old D&D cartoon, the Dungeon Master was a powerful but not omnipotent entity, and any power he used had consequences. He was also helping the PCs, not hindering them.

Something like this, I edited my original post to spew some of my thoughts on going more along that route, of a DM like entity instead of it being the DM themself.

I think it sounds just too meta. The moment you introduct the DM and the players as actual in-game entities, you rob the characters of everything.

You are completely right. I do not want to rob them of everything. The concept would be that the DM doesn't control their individual actions, or the actions of other people, but instead tries to change the world to push the players in the direction they want, but players have their own level of autonomy. Also, as previously said, I think instead of the BBEG being the one true DM, instead having this be a DM like entity.

[Zhorn]

I'd say cut out the DM part, and reframe it as something more fitting to the narrative of the story without the meta-layering. As other have said above, that aspect sounds like an immediate turn off.

high powered genie
trickster spirit
fallen demi-god
high level mad mage

The base concept is a long lived individual (potentially immortal but not proven to be unkillable) who's acting as a puppet-master of realities for their own personal interests, but not directly the antagonist for a few adventures.

I'm thinking go for a mix of The Elder God from the Legacy of Kain/Soul Reaver series with a mix of Gabriel as the Trickster god in Supernatural.

They have a personal goal for the realities they attach themselves to, setting up events in the world to feed off the consequences.

While everything is running as planned, they are mostly just bouncing about the world as a generic trickster seeking entertainment throughout their eternity. BUT every so often, when there's a big enough shift is how the world is being run, they get more directly involved. Guiding and nudging key figures into position, inciting actions and responses between groups, plucking on those puppet strings to shift things back to running on 'their' plan.

One campaign the party is getting snippets of information and rumours about a power behind that arc's BBEG.
Next campaign there's a mysterious benefactor helping guide them in their quest.
Following on is an 'ally' who seems to always encourage goals slightly askew.
Drop breadcrumbs that these could be the same entity, but don't explicitly draw attention to it or make finding out that connection a goal.

[Wizard_Lizard]

Alternatively have the fight be in limbo. The BBEG is a master at controlling the matter of raw chaos and can form the world around them as they see fit.

[firelistener]

Really try to show the players their life is out of their control, and the party never knows who is pulling the strings.

This isn't a good goal in my opinion. It sounds cool, but making players feel powerless is completely the opposite of why most people play D&D. It's heroic fantasy, so let them really feel like heroes and they will probably be happier for it.

Tarrur being just a cartoonishly evil villain sounds perfectly fine to me. A lot of players I've had just really like the simpler villains because they can feel confident in doing Good or not. When it's unclear if the villain is actually capital "E" Evil, players will often hesitate and second-guess a lot when trying to role play because it's less obvious what they're character would do. That can be frustrating for some players.