How long has Mayuri been around??
When talking about the longest lasting members of the Gotei 13, the default three always come up.
They are of course, Ukitake, Shunsui and Unohana. But where does Mayuri fit into this?
When looking at the TBTP arc, Kisuke notes that Mayuri is the only prisoner to be in solitary confinement.
He also states the fact that when you are a Gotei 13 Member, technically, you can't leave and you are instead transferred to the Maggots Nest
Clearly this means that before being appointed to the TRB by Kisuke, Mayuri was in the 13 Divisions. Not necessarily in a captains position, but a shinigami in soul society nonetheless.
Going to the chapter where the G13 meet Squad Zero, there is clearly history between Shutara and Mayuri, because it looks like it's not the first time that she's broken into his lab.
Considering that, upon his arrival, Kisuke says absolutely nothing about Shutara, and add on the fact that she wasn't mentioned during the TBTP arc when Kisuke made the TRB, we can assume that Mayuri had his own lab or institute prior to being imprisoned. Which is probably why he has so much contempt for working under Kisuke and then being referred to as his disciple throughout the story.
It's clear that he was around during the time of the first war on the Quincies (he told Ishida that he has already finished "researching" them). I think the reason that he was imprisoned is because he may have taken these experiments too far or he had committed a crime relating to his scientific work. Also another thing to add is the fact that he knows that Yama failed to kill Juha Bach 1000 years ago. Now I can't jump to conclusions but to have that information means:
- Either he was told about it (This is more likely tbh)
- He has an affiliation with the Gotei 13 from 1000 years ago (The mercenary killers that Juha talked about). So maybe Shutara was as well, until she skipped happily away to the Zero Division (guess we'll find out soon)
So yeah, I'm hoping there's more to Mayuri than just crazy psychopathic scientist, and I hope Kubo digs into some Shinigami history, not just Mayuri's but other characters as well. Eagerly awaiting another TBTP arc to clear up loose ends.....