[LKK]

Spoiler for ep 8:

The end of the episode gave me some insight into what might have caused Soushi to act as he does. While Ririchiyo's family treated her as a good luck charm, perhaps Soushi's family treated him as a slave from birth. When he said that he didn't know how not to act like a dog with those accompanying flashbacks, I got the sense that for all his life he's been someone's servant, more accurately someone's slave. If he was trained from birth to be obsequious, he might not know any other way to behave around people. Especially around someone he truly respects, admires, perhaps even worships? I think it's clear from the OP that Souishi was the one who really responded to child Ririchiyo's letters to her fiancee. Perhaps her letters brought him some solace in an unhappy existence? With those thoughts in mind, I'm even more curious as to how Soushi came to be her bodyguard and how she "saved" him as he claims.