The queen got the throne but the brother wanted it. And he's the bad guy, in alliance with the Vex, to seek the throne for himself. The queen is...aware ("often when we guess at other's motives, we reveal only our own"). That is why she helps the guardian's agenda, and says that one day she will call on him, and expect him to answer. That would also explain why he's...not too thrilled about sending the guardian to the Black Garden in their attempt to destroy "God" and repeatedly tries to sabotage that effort. Hmm I wonder how close to hitting the mark I am. Lol