What if Kaido really had no intention to kill Whitebeard but to save Ace as per Yamato's request? In exchange, Kaido would recruit Ace for his crew. Kaido is often soft-hearted towards and care for his crew. Kaido wanting to have another card (Ace ♠️) to put in his collection is a great plot twist. Shanks and Kaido confronted but Shanks never believed Kaido's reasoning so Shanks stopped Kaido from reaching marineford.

King Queen Jack Ace 👀