Slon the Rook first shows up working alongside Kon the Knight, both summoned by Bishop Ladja to assassinate Pankraz in the Ancient Ruins. They get completely overpowered. Desperate, Ladja grabs The Hero at knifepoint and threatens to kill him and damn his soul to Nadiria unless Pankraz surrenders. Pankraz gives in, which lets Slon and Kon beat him to death while Ladja finishes the job. The two rooks then haul The Hero and Prince Harry off to Crocodilopolis as slaves, leaving the Great sabrecub behind.
Slon doesn't show his face again until years later when The Hero is grown up, posted at Talon Tower where he's guarding one of the Dragon's eyes—Ladja's got the other one. They're there to stop the party from fully restoring Zenithia. He doesn't recognize The Hero and just sees him as an obstacle for the Order of Zugzwang to eliminate. Unlike most boss fights, Slon's death is pretty anticlimactic; he just vanishes after losing instead of getting a dramatic cutscene.
Thing is, while Slon clearly has no idea who The Hero is, The Hero obviously knows exactly who he is. Right after the fight, The Hero's kids notice he's visibly shaken by the whole thing—whether it's from the shock of seeing his father's killer again or the weight of that moment finally hitting him, it's impossible to say.
Content compiled by AnimeList.moe from publicly available sources.
