There's already implementation for "hirelings with no attached plot elements," so I was surprised to find that characters we've saved or encounter who just disappear after their stories can't be hired. It would be a lot cooler to have a character who we have some minor history with in our party than some random character. Basically, any combat capable character we fight alongside, rescue, or interact with who might be interested in fighting for coin or might just want to come along with us who disappears from the game after our interaction or has no more meaningful interactions could be added to the Hireling pool after they're encountered. Generic voice lines would be fine if the actual VA for those characters didn't record enough dialog for them.