The story arc with the snow-girl who falls in love with a human man... And her mother who lost her own.
When the bakemon Kuin mocks Ushio's weakness, stupidity and lack of training compared to its master Kirio, Tora beats the crap out of it, then says to Ushio: "I don't know why I got really p*ssed off when he was saying that crap about you... BUT I still hate your guts!"
In episode 5, Ushio stops Hyou from killing Tora, partly because Tora has saved his life a few times already. But also because he doesn't want Hyou to suffer from He Who Fights Monsters, by killing the wrong monster for the death of his wife and daughter. Though Hyou takes it out on Ushio a little bit, he does eventually calm down, and even patches up Ushio a little. Tora then decides against eating him while he was sleeping and recovering from all the wounds suffered due to his protection.
In episode 14, Tora finally admits he hangs out with Ushio not just because he is his food. He actually has fun when they are together.
In episode 16, Tora threatens to eat Ushio if he starts to turn into a youkai, as seen by long hair growing out of his arm. Izuna, a small youkai helping them, then asks Tora if he's really going to eat him. Once Ushio regains control, Tora seems disappointed that he can't eat Ushio, but Izuna notes that he actually seemed relieved that Ushio came back to his senses. Tora then tells her to shut up while using his comical face.
The entire animated short from 1993 "Tora and the Kitten". Just AWWWWW.
In a strange way that only works between the titular characters, in true tsundere fashion, Tora shows he's forgiven Ushio by yelling insults at him. He catches on and calls him names just as well, giving them both the strength to fight back against Hakumen no Mono together.