"Kagami, about your relationship with Izuna–" "Just because Sensei revived him with edo tensei does not mean he's a zombie nor is our relationship necrophilia in any way, shape or form! Get over yourself, Shimura!"
OKAY, but my mind took this somewhere so freaking bittersweet.
I’m imagining this would happen in a semi-canon AU, where Izuna was killed by Tobirama during the war. And Tobirama knows full well it was kill-or-be-killed between them, that he didn’t have the courtesy of fighting someone who didn’t want him dead (whereas Hashirama and Madara were reluctant to actually kill each other).
That being said, the war’s over. Konoha’s built, and the peace looks like it’ll last. Madara’s sane here but he’s still grieving, and Tobirama knows that (sans war) it’s his fault.
So what does he do? The only thing that would ever make the hurt even a little better: he decides to bring Madara’s brother back.
Imagining the Edo Tensei to be an actual resurrection sort of thing here, so Izuna ends up back and fully alive, and learns to live and love in the village. And Tobirama and Madara might never be close friends after what’s been between them, but they reach a sort of understanding at the very least.
…meanwhile Danzo’s writing the first ever zombie stories in hopes to warn the future of what he sees as a coming disaster, and Kagami’s just happy to ignore him (and switch his ink with the kind that disappears).