From the Backseat

Kadence Lockwood and her two sisters, Nikkole and Kristen, are thrust abruptly into Sam and Dean Winchester's lives when their hunter parents are murdered by Azazel. When Kadence learns that her Godfather, John Winchester, is hunting the demon the killed her parents she wants in, and her and her sisters will use any means for their revenge. Eventual Sam x OC, Dean x OC, Cas x OC.