Eltrio is a character in Square Enix's Dragon Quest VIII: Journey of the Cursed King.
Eltrio was once the Prince of Argonia and elder brother of it's current King, Clavius.
As required by tradition, Eltrio had to undergo the rite of passage which involved defeating an Argon lizard to obtain it's heart and succeeded in doing so.
He eventually left the Kingdom and the throne in pursuit of a woman he met and hasn't been seen since.
The woman Eltrio was in love with was Xia, a Dragovian. At some point, he presented her with the Argon ring made with the heart he retrieved. Because Eltrio was not a Dragovian, both he and Xia were forbidden to remain together as her father Chen Mui, took her back to the Dragovian Sanctuary.
Eltrio attempted to journey to the location, only to die outside the sanctuary's gates, where he was buried thereafter.
Unknown to Eltrio, Xia was pregnant with his child, who later was banished from the Dragovian Sanctuary due to his mixed heritage.
Xia herself didn't survive during the birth of their child and was buried with Eltrio, by Chen Mui who did so as atonement for keeping them apart. He also took the form of a mouse, so that he could keep watch over the now orphaned child.