We're talking about the hound here right? Good. He's alive? Is the mountain alive too? I'm pretty sure he died. He was poisoned even. But yeah, I agree. I always fantazised about a final showdown between Gregor and Clegane.
Pretty big spoiler ahead Seriously, this has only been vaguely hinted at in the TV show The Mountain becomes a Frankenstein-esque guy, and becomes the Captain of the Kingsguard.
ffs, read a damn book Jaime leaves with Brienne of Tarth ( I don't tremember why, I think to lead him to Lady Stoneheart) and Robert Strong is mad captain of the guard in Jaime's absence.
He wasn't elected at all. The first and only time he's seen is when he picks up cersei when she falls during her "walk of shame". I've googled "robert strong commander kingsguard" and there's nothing about him being raised to commander, only to one of the MEMBERS of the kingsguard. Like I said, Jaime is the commander.