We know Shanks blocked Kaido from entering the Battle of Marineford, and the assumption was that Kaido’s primary goal was to escalate the conflict given his desire to start a global war.
But the fact that there’s a potential connection between Kaido and Ace means there could have been more going on. It really makes you wonder if Kaido was in any way motivated to rescue Ace from Marineford.
I think Shanks at least proved that he was trying to save Ace by first approaching Whitebeard and trying to prevent Ace from going after Blackbeard in the first place. I think Shanks is a pretty complicated character.
Getting a read on Shanks is a little bit difficult, but I’d say he’s likely guarding the way to One Piece, in full understanding that only the right person can inherit the treasure at the right time – the person Roger is waiting for. Shanks is trying to keep the peace until that time comes. I think Shanks has fundamentally good motives, but still means making hard choices. Shanks tried to save Ace, but Ace made his own decision to face Blackbeard.
Kaido intervening could have meant rescuing Ace, but Shanks also understood Kaido’s desire to incite a global war. By escalating the conflict at Marineford, the world would have become even more chaotic. Shanks arrived to end the war – much like the Five Elders, he seems focused on maintaining balance, preventing the seas from becoming too turbulent. Stopping Kaido was a decision made ‘for the greater good.’ At least that’s my interpretation.
Here my full video review:
*Theory by StrawHatJedi