This idea was sparked by the EsperiArt Faction Swap topic. There are too many ideas for design changes, though, so I settled for the one closest to my heart - one connected to one of my OCs: Erin.
As canon stands, I envision both Erin and Cyran to be dead by the end of the true end game, were Merlin somehow defeats the evil for good and Esperia is basked eternally in Dura's light.
But, with a bit of cheeky freedom, there could be a more wholesome ending for these two as well. ;-)
Cyran's deep connection to and power over Dark Magic, which I assume is very similar to Hypogean Magic, allows him some sort of compatibility with anything Hypogean. So when he died in battle against Merlin (after holding out against not just one Celestial before that), his body (and soul) was swallowed by Hypogean darkness. Erin, still present within Ygdris after having been consumed, manages to take control over this entity after Merlin does his final blow against the darkness. Merlin, the lock and Erin, the container, finally served their purpose for a brighter Esperia.
Now the queen of Hypogeans, Erin retreats at first, slowly building a new connection with Esperia and its inhabitants. Merlin, watching over the Celestials, helps over centuries in the reconciliation process.
In this form, Erin is able to grant Cyran a new life. His soul can accept the new body given to him, but the merging process is not easy. Despite his strong bond with Dark Magic, his soul might not withstand the Hypogean body. But after some time of struggle... Cyran does return to take up the mantle of king to the Hypogeans, by Erin's side. He is a polite and formal ruler, fair even, provided you do not cross him (he will grant warnings). While most will encounter him with a serene smile, a few will find themselves staring into a twisted smile just before they disappear never to be seen again.
