Well this character would have to be a guardian of the Holy Land, and probably a high ranking guardian. Who could such a character be?
Well obviously I’m going to go hardcore History Channel “Aliens” with this one but fuck it. This is what I would do:
I would give the Cerberus fruit to the Captain of the Holy Knights:
Now I know I just lost half the readers of this thread so fuck it, let’s go all-in on this. Lol
So imo the best thing Oda could do with Shanks is to hardcore subvert expectations and make him evil. There’s just no way Oda can write Shanks as a good character that will end up being memorable or satisfying, so give us Captain Holy Knight Shanks who is the chief guardian of the Celestial Dragons and is a Celestial Dragon himself.