Future STAR WARS Plot Ideas If (SPOILERS) Had Lived
As those of us who spend way too much time on social media know by now, there's a lot of discussion out there about The Rise of Skywalker and in particular a lot of fans are upset that
Ben Solo, aka the Dark Jedi and First Order Supreme Leader Kylo Ren, dies using the Force resurrect Rey, who fell in battle against her undead grandfather, none other than Emperor Palpatine. Given how The Last Jedi converted me to the "Reylo fandom" and the two of them are absolutely Adorkable when they have the Big Damn Kiss, this was a tad bit disappointing.
(Seriously, look at their facial expressions. It's so cute.)
However, given the magnitude of Ben's crimes, it would have been really awkward for him to just show up at the big Resistance victory party, especially given how many people he'd grievously wronged (mind-raping Poe, killing Chewbacca's best friend, lots of battle casualties for the characters without names) are all there and happy. That's why Redemption Equals Death is such a common trope--someone who'd done that much bad, even if they switch sides and do something useful (kill Palpatine the first time for Anakin, revive the dead or dying last Jedi for Ben), isn't going to be readily accepted by the good people.
That said, if one is willing to put in the work, one could come up with all sorts of interesting plots:
*Ben, owing to his brief tenure as the Supreme Leader, provides the intelligence necessary to more quickly destroy the First Order forces that weren't involved in the battle at Exegol. Realistically they'd be overextended (the movie references "free worlds" so the New Republic hasn't yet been completely conquered) and there's a major leadership vacuum with General Hux, Allegiant General Pryde, and Palpatine dead. Given how the First Order was formed out of Imperial survivors who were allowed to remain, albeit disarmed, or die-hards who fled to the Unknown Regions, nobody is going to want a negotiated peace or anything resembling the First Order left intact. Think WWII unconditional surrender.
If you want to torture Ben, this means he has to sell out people who were loyal to him when he was evil, including people who might well have been actual friends. Furthermore, as my uncle pointed out, "no one trusts a traitor" and Ben has betrayed both the New Jedi Order/Republic and the First Order at this point. He'd need to provide some really good stuff, with independent backup. If you want to crank the awkwardness up, he might even have to work with Finn, whom he'd deliberately sadistically injured but not killed in The Force Awakens, to engineer defections of stormtroopers from First Order armies units he knows are prone to discontent and mutiny. More on the drama with Poe and Finn next...
*Although Poe, Finn, and Rey are the new power trio in the vein of Luke, Leia, and Han in the original trilogy or Ron, Hermione, and Harry in Harry Potter, Rey's romance with Ben could destroy this. In The Force Awakens, Ben mind-raped Poe in what's clearly an extremely unpleasant process and let's not forget the lightsaber-to-the-spine with Finn. Although Poe only saw Ben with his mask on, it's my recollection he was unmasked when he fought Finn and Rey the first time. They're going recognize Ben (or at least Finn will and he'll tell Poe) and they're going to feel massively betrayed. Given how they're two of if not the two senior leaders of the Resistance at this point and will likely have correspondingly high positions in the New (New-New?) Republic, Ben might end up exiled or even a fugitive and Rey will have the sadistic choice of abandoning him to stay with her Resistance friends or joining him.
*When Chewbacca learns of Leia's death, he falls to his knees in agony and pushes away any attempt to comfort him. As someone pointed out on Twitter, this is the third friend he'd lost because of Ben--Han got straight-up murdered, Luke burned himself out Force-projecting to distract Ben from finishing off the Resistance at Crait, and Leia burned herself out Force-projecting to jump-start Ben's redemption. Although Chewbacca flew Rey to the First Order fleet in The Last Jedi in order to facilitate what everybody hoped would be Ben's defection, at this point he may well be of the opinion, "Screw that kid." He might be violently (emphasis on violently) displeased to see Ben again. I recall Han's comment about Wookiees pulling arms out of sockets and depending on just how remorseful Ben is for his bad deeds, I'm imagining him letting him do that.
*Per the above, the fleet that arrives to relieve Poe and his pilots over Exegol seems to have been organized by Lando. Lando, Han's longtime friend, friend enough to Luke to help him with his "rebuild the Jedi" project, and given his past I'm pretty sure "send Leia my love" was him trying to hit on Leia like in The Empire Strikes Back now that Han is no longer in the picture. Even though per some of the new-canon material he was a sort of uncle to Ben as a child, he's not going to be happy with him either. Since it was Lando who brought the fleet to Exegol and he has actual governing experience (running Cloud City), I'm imagining him as the new Chancellor (with Poe probably being naval commander and Finn being the commander of ground forces) once the Republic is re-established and he'll be able to express his displeasure far more forcibly than just punching Ben in the face until he wears out his arm.
*Given how Snoke had forbidden Ben's true name from being spoken by the First Order and most of the galaxy might be only vaguely aware of him (as opposed to Kylo Ren), he's not going to be most hated man in the entire galaxy, at least right away. However, word is going to spread and then he will be.
Perhaps the Resistance leaders agree to accept him back to help clean up the First Order survivors (depending on how well-known his defection is, he could order surrenders or withdrawals out of Republic territory as Supreme Leader in addition to the intelligence he can offer), but as word spreads, popular outrage builds. Think how in the new-canon novel Bloodline, the revelation that Leia concealed that her father was Darth Vader caused a massive popular outcry and derailed her political career. And in this case, said outrage would be far more justifiable given Ben's actual crimes.
Ironically enough, if a surviving Ben works with Rey to rebuild the Jedi Order, a separation between the Jedi and the New Republic--either the Jedi Order has to be rebuilt outside the Republic's borders because one of its two new leaders is going to be shot on sight or Rey and Ben are allowed to remain (probably as a favor for Rey rather than out of any love for Ben) but the Republic's leadership doesn't like or trust them--might be for the best. The Jedi aren't going to be part of the political system with all its distractions and corruption and can basically serve as an order of teachers, mystics, and knights-errant (I'm thinking a visit to Canto Bight to free some child slaves and recruit broom-boy for the New Jedi Order is a good idea) rather than a close ally or arm of the state.