I feel like the patb community moved on from Future Brain WAY too fast.
We had a version of Brain that was completely broken in the future. So broken and driven mad that he thought it'd be a good idea to go back to the past and eliminate Pinky because he believed he was the source of all his problems. He didn't even have a problem with the idea there was a chance he would cease to exist in the process (or that he could create a split in the timeline depending on what theory of time travel you go with; I personally subscribe to the multiverse theory but we're assuming he's trying to rewrite history and erase himself so Present Brain doesn't turn into him).
It gave Present Brain a dilemma that could have been fleshed out or revisited at some point; The World or Pinky
Yea, everything goes back to the spin-off, doesn't it?
He was faced with a choice: Keeping things the way they are, or eliminating who he believes the source of all his problems are.
This was something touched upon in season 2 as well in "Plight of Hand"; The Brain vs The Heart.
In Future Brain, Brain didn't really get to make his choice verbally but attempted to beat himself into submission for even considering to eliminate Pinky from the equation.
And from the ending of the episode, we understand Brain is just doomed to drift towards Pinky, no matter the form
But then that's the last time we see him. Ever.
Absolutely criminal.
Having Brain properly confront himself would have been my endgame, but you can't rewrite the past...














