Well, by the time Cyrus and Aeon are recovered from the Distortion World, it’s been almost 6 years since the events on Spear Pillar. All the admins have moved on (or begun to move on) from their Galactic days and gone their separate ways. Jupiter and Mars got harsher sentences due to being at Spear Pillar, so mostly have dropped out of the public eye, while Saturn moved up to Snowpoint and became the Gym Leader there (as mentioned in this post). Prior to becoming the Gym Leader, when he was still new to the city (well, it was his hometown, but he hadn’t lived there in years), Saturn ran into Archer, who had also come there because it was so remote. The two ended up talking and discovered how much they had in common, which led to them becoming roommates, which led to a romantic relationship starting. A few years later, they’re married with a daughter, Ceres, and are generally happy with where their lives are – until the reappearance of Cyrus shakes everything up.

When they first are brought back from the Distortion World, Cyrus and Aeon move in with Cyrus’s sister, Johanna, in Twinleaf and live there for a while as they acclimate to being back in the normal world (especially since Aeon had never lived anywhere but the Distortion World). All of this was intentionally kept under wraps since Dawn knew any kind of attention was the last thing Cyrus and Aeon needed, so Saturn wouldn’t have found out via the news or anything. So the reunion between them only happens at Cyrus’s own pace, which takes a while. Eventually, and with some encouragement, Cyrus decides that he really should reach out to Saturn and tell him about Aeon, since his former right-hand deserves that much at least.

This is Cyrus though, so he basically just… shows up at Saturn & Archer’s home in Snowpoint with little Aeon in tow, so needless to say it’s A Lot for Saturn to process. He’d accepted that Cyrus was gone for good and moved on with his life and now all of it had come crashing back without warning, so it takes him a while to work through his reactions and feelings about it. With Aeon, however, it’s easier than dealing with Cyrus. Saturn is already a father, he knows how to handle that, so he does his best to bond with Aeon and invites him over quite frequently. He wants to be part of Aeon’s life, especially since he does worry a bit about how he’ll turn out if Cyrus is the only major adult influence in his life (which leads him to bond with Johanna unexpectedly since she’s also very involved in her nephew’s upbringing for the same reason). Since Cyrus usually comes with Aeon on his visits, the two eventually have to confront everything and end up having a lot more heartfelt conversations than they’d ever had, being more honest with each other about things. Saturn can see that these past years have changed Cyrus, and Cyrus has a lot to ruminate on seeing this side of Saturn where he’s not just devoted to him and Galactic. (And Archer just keeps taking Aeon and Ceres on day trips since the tension at home between his husband and his husband’s sort-of-ex is so thick.)

But over time, now that there’s no Galactic backdrop and both of them have had time away from that and each other, Saturn and Cyrus are able to develop a better and healthier relationship. While Archer doesn’t have any kind of past with Cyrus, he knows how much Saturn still feels for him (he was/is the same with Giovanni after all), so he supports the reconciliation and makes the effort to bond with Cyrus as well. Eventually, Cyrus doesn’t really want to keep living with his sister anymore and spends enough time up in Snowpoint anyways that he (and Aeon) just move in with Archer and Saturn. So yeah, basically Saturn meeting Aeon and Aeon existing at all is what leads to him and Cyrus reconciling ultimately since if there hadn’t been a kid he might not have been able to bring himself to confront Cyrus or at least it would have been a lot slower and probably wouldn’t have ended in the throuple ending.