Sansa is menstruating. Why are hounds here?

The hound is the person who appears beside Sansa when she has her period. However, there is no relationship between them. First of all, Sansa is a fictional character in George Raymond Richard Martin's series of novels of ·R·R· and Ice. She is the daughter of sansa stark, the protagonist of the story. Secondly, the hound is one of the main characters in another fantasy novel's Devil Hunter. He is a famous demon hunter and has no direct relationship with the characters in Fire and Ice.