What Makes The Gorosei Obliged To Serve IM

I'm not entirely sure how much autonomy IM has. The gorosei had already made the decision that there would be a cleansing even prior to meeting IM. And the way she walks about the castle, veiled, seemingly kept away from everyone except for a servant and the gorosei, her existence kept hidden, I'd have to ask whether her secluded, secret nature is her decision or not.

Basically, I'm not ruling out im being a vital figurehead for the gorosei, who are still mostly running everything. I mean, in japanese history that's a rather common situation with the emperor and then the politicians below. Emperor was still "Officially" in charge, but the reality is more murky. But even with that I still think that im is very involved in whatever happened during the void century to wipe the ancient kingdom off the face of history. And given the crown and the throne, that's pointing to both factors being involved in the gorosei, at the face of things, being subservient to her.


As we've known for years, the gorosei control the world through the navy, and evidenced by shanks meeting they might even control the pirate world, but now to know that they serve a single king is quite a shock. So to jump into topic

What qualities does IM have that qualifies him as leader of the world?

1. Is it physical prowess?
2. Personal control of an ancient weapon?
3. Simply bloodline
4. Something else?

State your opinions.