I’ve been watching Inuyasha, and InuTaisho definitely favored Inuyasha (possibly due to him being half human), or maybe just didn’t care very much for sesshomaru (possibly because he hated/killed humans).
Even though it seems like dog demons in general don’t interact with their children very much after they become adults, when InuTaisho saw Sesshomaru becoming/being bad he really could’ve have done more than just cross paths with him occasionally, offer advice, and then leave again.
Like maybe he could have asked Sesshomaru to travel with him under the guise of showing him how to be powerful, but in reality take him on a journey to ensure that he didn’t become/stay bad. (^ u ^)
EDIT (because I can't double post):Sesshomaru was terrible to Kagura, and I say this as someone that likes Sesshomaru.
He refused to help save her life while she was alive, and only went to try and save her while she was literally already dying.
The fact that he was willing to revive her shows that he probably did care for her quite a bit, but in the end he decided to help her way too late.
Kagura deserved better. (U - U)