Littlest Urge
Durge defies Bhaal, and he destroys all that he made them, all that he knew — maybe even reduces them to a puddle of blood, like Orin. Durge wasn't even born, so maybe when Withers brings them back, it's just a dragonborn egg or something.
Maybe Durge confided in someone the letters they found about them and Gortash, and the subconscious, positive feeling they get with him, and so their confidant brings the egg to Gortash, tells him what happened.
Ultimately, Jergal wants to weaken the Dead Three, right? So maybe they convince Gortash to forswear his god, and Withers will protect him too. He wasn't made and killed like Durge was, so that kind of full reset is unlikely, but he fixes Karlach's engine as a gesture of his intent to be better, and they take down the Brain without Durge.
When Durge hatches and starts growing, it seems they've retained the love and trust for the friends they made against Bhaal's will (including Gortash), even if they've lost the foundational stuff like language and context.
The cutest little dragonborn running around to their various co-parents — getting a more assorted upbringing of morality and skills. They have a hatchling sibling in Xan, although he — not having Durge's preexisting relationship to so many companions — might have a more stationary household, only overlapping part time with Durge.
Finally being free, not ruled by fear, Gortash is turning over a new leaf — a journey he's sharing with a lot of companions. They're new at it, and trying, and they have some good role models to guide and support them.
