Responses
My theory is that bro's mind got fused with the calamity dragon's or got preloaded info from the dragon god that all calamity dragons require and thus he could indeed mean dragonkin.
My reason being that he mentioned being the plaything of the gods, which makes sense if you consider before the lightning dragon's death he was pleading that the calamity dragons are necessary to bring some sort of balance using destruction.
Another reason is when the sleep calamity dragon mentions how her feelings of hate and destruction for humanity isn't hers but something implanted in her instead. They're all chess pieces
My kin?
What does that mean? Or was he referring to the dragonkin?
Or he is saying that MC is his kin?