Season 2 would follow Jason being sent to learn by all the different teachers Talia finds him.
He is a lot more mellow and uses a lot of his time reflecting on his life (where he went wrong or if he ever had a chance at being good at all) we still have the flashbacks but this time it shows him being a crime lord, how manic he was and how horrified he is at what he did (looking at you tim)
He struggles with his morals a lot in season 2, lacking the conviction he had in season 1. Trying to find purpose while he feels so detached to everything.
He finds it somewhere between getting his ass kicked by his first teacher for the umptenth time and finding evidence that his teacher is a scumbag.
Jason kills his teacher after he learned everything he could from the guy. It's a twisted sense of justice but it's one none the less and he clings to it, keeping at it as he travels the world going from teacher to teacher. Killing them all when he is done with them.
(I think that part would take up like 3-4 episodes maybe? I do think there should be a whole episode dedicated to when he meets Lady Shiva and how he lets her die in an honorable fight as she always wanted)
Then he moves back to Gotham, gets his crime empire under control again and plans the perfect murder of one Joker. If Bruce isn't gonna save him from his tormentor then Jason will gladly put a hundred bullets in the Joker's body himself.
While planning he has to dodge the others as they try to get him to redeem himself. (I do think he apologieses to Tim at some point but only after everything has gone down with Jk) also at this point Damian has become Robin and Tim Red robin.
Anyways he will have his big show down with Joker, do some big villain speech and then pull the gun at Joker's head only to not be able to shoot. Imagine he hears the Joker's voice from back when he was a child ("left or right little birdie? Option A or B? Ahahaha")
And Bam! Batman comes in incapcitate a hysterical Jason who keeps saying "I can't do it, I can't do it, I can't do it!"
Batman being the bitch he is would try to take the Joker into custody but he can't because while he was busy with Jason little demon heir Damian al fucking ghul have chopped off the head of the Joker.
"Damian" Bruce would say horrified but Damian isn't looking at him, no he is looking at Jason.
Damian hugs Jason and says "he won't hurt you anymore akhi"
(Because Jason always protected Damian while he was with the league, they became brothers far before Bruce had any idea Damian existed and Damian would do anything for Jason. If that means killing the Joker so his brother can finally rest easy at night then so be it)
The last episode would be a bit like an epilogue i think, where Jason reflects on gotham before packing up his shit to go travel the world again
(Season 3 perhaps featuring start of the outlaws or his time with the all-caste)