A Circle-Situation:

The protagonist has been a part of the Circle since birth because the parents were part of it too.

The parents got killed and the protagonist is on their own.

Because they are underage they don't get killed or deruned, but sent into the New Yorker Institute.

Alec/Izzy/Jace/Clary help them with the trauma of the loss of the parents and show them what it means to be a responsible nephilim.