It is possible that something is going to happen to him during that side-story, so the writers decided not to use him for the canon material...You should be prepared for Count Keteratesse to be relegated to just a mysterious person who disappeared during the timeskip and whose fate is unknown (unless you read the aforementioned side-story). It certainly wouldn't be the first time something like that has happened in anime.LightningCount wrote: I'm still hoping for Count Keteratesse and his Geryon Kat to come back. But with all three Counts surviving this episode (two new, one old), I'm not sure they'll be able to fit him in. Then again, his sole line in Season 1 was something like "swear allegiance, or be annihilated." So, maybe he'll emerge as one of the dissenters to Slaine. That would be awesome. Especially since there is supposedly a prequel/side-story manga ongoing in Japan where he plays a part (that's where I got the official names of him and his mecha from via Wikipedia.) I get the impression that he is a Count of leadership more in the league of Cruhteo.
But then, I have not read the side-story, so I have no idea what it is covering...yet it is a possibility that he already died and the manga (i am assuming it is a manga) will explain why.