My reason for shipping them isn’t terribly exciting. I wanted to think about what the evil team executives/commanders/etc were up to and wanted to portray at least one of them as having essentially ‘run away’ from their past and started over a crime-free lifestyle (without having faced the law for their previous crimes.) Archer and Saturn both seemed like good choices for the role. Both were ‘interim’ leaders of their teams (hence the ship name). Archer is the one to choose to disband Team Rocket at the end of HGSS and Saturn claims to have learned that extremism is never the answer at the end of DPPt. As such, it only seemed natural to pair them together since they shared so many similarities. 

As for how it happened in universe, after disbanding Team Rocket, Archer decides that, rather than face justice, he would rather just start his life over in a new region where he was less well known and not deal with all that pesky ‘going to prison’ stuff. He ends up deciding to head to Sinnoh, where Team Galactic had also recently faced defeat (as HGSS and DPPt take place at the same time, roughly). Saturn (who was now going by his civilian name of ‘Sasha’ now that he no longer worked for Cyrus) had had a similar idea to flee into the more remote reaches of his home region and start over. The two happened to meet up in Snowpoint while searching for a place to live and figured they might as well be roommates to save on costs (Archer had brought considerable funds from TR but was wary of spending it all so as not to attract attention). They buy a small house in Snowpoint together and split the costs for bills and the like, both also finding local jobs (Archer puts his leadership and number skills to work as an analyst for a shipping company and Sasha returns to his old passion for folklore as a guide at the National Park surrounding Lake Acuity and the Snowpoint Temple.) Neither of them knew the other’s backstory and both were trying to keep their own backstory a secret from the other. It was essentially a sitcom plot, haha. Over time, they begin to develop feelings for each other, but never mentioned it since they didn’t want the other to reject them after finding out their criminal past. Of course, they both eventually do find out (both the backstory and the feelings) and it was probably very melodramatic and ended in a makeout session. Amusingly, when they make their relationship public to their neighbors and coworkers, it turns out everyone had already assumed they were a couple. After a while they have a small, low-key wedding that is mainly just a few friends from Snowpoint (Archer has no desire to contact his brother and Marcella wasn’t interested in catching up with her old coworker at this point, even if he was getting married.) Not too long after they end up having a daughter together, Ceres, who grows up having no idea of her fathers’ pasts until she finds out accidentally while on her pokémon journey as a teenager. Luckily, Ceres didn’t mind much and actually thought her fathers’ stories were kind of cool and a bit like a dramatic novel plotline. As for what happens to Ceres, I already talked about her in the post I made about Callisto!