The Last Mistake

What is King Maven's greatest weakness?
A girl.
A Red girl
The little lightening girl.
Told from Mare's PoV, a spinoff of King's Cage focusing on one aspect; Maven's desperation.
Let me be clear, the characters and plot belongs to the rightful owner, Victoria Aveyard, the author of Red Queen trilogy.
"I threw myself into that fire, threw myself into it, into him, and let myself burn."
― Sarah J. Maas, A Court of Thorns and Roses