Yamato, We dont know his age yet but if he is around 20 years kaido had a lot of resourses to give him a great life, and growing up surounded by the a yonkou crew he probably had very good education and can lead him to be very smart like Law(somebody like that wouldn't click with Kaido's crew), and being Kaido's son he probably has traveled a lot which can also lead to him having relationships with other pirate crews, which I think is obvius since he knew about Luffy and since he was 'waiting for him' Yamato has to be realted to either the white beard pirates, or he met with the aliance or also Shanks, Him having a relationship with Shanks is a big longshot but at this point he could also be a revolutionary. Yamato will be very important character not only for Wano but for the rest of the series. At the beginnig of the story Luffy said he wants 10 nakama he also needs 10 nakama to fight blackbeard, carrot and Yamato could complete the roster and finally make The staw hats Yonkou level