Afterlife
Tobirama wasn't sure what he expected from the afterlife, but a fascinating mix of past and future tech wasn't it. Through a little cell phone everyone has, they're able to access something called the "Memory Viewer", where they can see into the minds of their alternate selves. He initially intends to use it for scientific discovery (and he still does, to an extent), but the intimate relationships his counterparts have are strangely intriguing.
Through viewing these memories, he discovers his own hidden desires and develops a polyamorous relationship with his brothers, Madara (of all people), the Uchiha's brothers, and a few others. The relationships don't always run smooth, but they have an eternity to make everything work and a peaceful world to explore.
(Some of the chapters contain rape, which is warned for at the beginning of each chapter. None of the afterlife scenes contain noncon {that would, in fact, be impossible. They can go intangible if they don't want to be touched}. Yes, the chapters contain a lot of sex. There's also character introspection and developing relationships.)
(Summary edited: 10/2/2019)
{https://www.pillowfort.social/KaelVercorian}