The seven princes share a father but have different mothers. One possible setup is that the empress died young and her wise successor treats them as her own. They grew up together, share a deep bond, and are far closer than ordinary royal brothers.
The court seems peaceful on the surface, but undercurrents are swirling beneath it: foreign tribes, powerful ministers, and forces from the martial world.
Each of the seven brothers has his own strengths. They complement and support one another as they face the storms together.