https://wikiofthrones.com/why-....was-the-hound-so-pro

Why was the Hound so protective of the Stark girls in Game of Thrones? - Wiki of Thrones
wikiofthrones.com

Why was the Hound so protective of the Stark girls in Game of Thrones? - Wiki of Thrones

The Clegane brothers had a younger sister, and one of them might've been responsible for her death in ASOIAF.