Great Middle Grade Reads discussion

I've just finished the three books. It's a great series, So glad to see they are making a movie out of it. The characters are still circling in my head. Especially Brevin Conner, he was so key in the ending of The Shadow Throne. But I don't get it. I couldn't find any fore-shadowing that made me think afterwards, "Oh, that's why!" or how, or when. Were his actions brushed aside in that line about being in the shadows between black and white, or have I truly missed something?

i started reading the series but it was popular and i cluldnt get it at my library

Discussing Brevin Conner entails a spoiler alert. For those reading on: The three boys competing for the chance to impersonate the crown prince bond together in spite of the competitive situation. I see Brevin bonding but resisting it because of his desire for the crown. He shows mixed feelings throughout the series, enough to convince the prince (rightful king) that he can become a loyal part of the royal team. The strongest example is the Brevin could have killed the prince early in the second book but doesn't do it.