Not really yan is 2 faced, he always balmes plantz when callian is not there something like why plantz never helped callian before (especially the time og callian still alive) but Yan never did anything for callian either, that's why readers doesn't really like Yan's character, plantz is a crown prince regardless he should be respected this is something novel Yan doesn't have, knowing how callian loves plantz this makes readers furious, it's like there's a spy. We're still waiting for his character development though I'm pretty sure the author wouldn't make it stay that way when author made callian's character to be a loving brother for plantz.
Plants threw a knife at him, and the way his father has a position to treat the king casually, combined with Yan not seeing anyone except Calien, I can understand his reactions tho. He is a mother hen, but he is his father's son so not much of brain, as stated repeatedly, his character is that of a poodle, bark at everyone else except his master. I dun think there will be any change in his character in the future.
I dun get the Yan hate i keep seeing on tt vids. He is an elephant whether he had claimed the position or not. And he was the only one by Kalian's side, both old and new while they were powerless.