These are placed in the correct order.
Hypothetically, if Kizaru were to retire so that he can smoke weed all day then who should replace him?
The newest addition to the animal + color themed Marine character is Black Horse. The opposite of Black Horse/Kurouma would have to be White Snake or Shirohebi. Because Kurouma isn't an admiral then it is safe to say that Shirohebi probably won't be.
Since the rat is situated close to the bull and the tiger then my assumption would be that the rat is the next admiral. Orange Rat does sound cool ngl.
A rat is a sneaky little animal. What is a rat in slang term? It is a person who abandons or betrays his or her party or associates, especially in a time of trouble. Basically an informer. This is should be his personality.
He should be someone who unintentionally reveals trivial secrets to his enemies while the rest of the Admirals shake their heads. Though his methods are questionable and one may even question how he became an admiral in the first place, Orange Rat's strength is unshakeable in terms of power and madness.
He can be that person who both enemies and allies trust with great caution but in the end it benefits the Marines. Betraying Justice, anyone?