Volume 1, Side Story 1: Beloved Bruce's Duty.
I reread it and while Bruce doesn't TOTALLY trust her, he thinks of her being more like an animal, she doesn't move without a reason. Even brings a bone to apologize to her... which she correctly calls out as "proof of an improved relationship"
according to the LNs, he kinda is. Serena even holds something resembling fondness for him.
there's a side chapter from his point of view that he originally singled out and attacked Serena because she was dangerous... but he realized later that she was only dangerous because he was intruding on...
Pretty sure I said this a few chapters back, but Celestine has ALWAYS been Celestine.
It's not so much that Reincarnator Celestine and OG Celestine are separate people so much as the shock of the wedding ceremony was enough to awaken her memories of her past life... where she was into DILFs...