Talk:Tatara/@comment-77.208.3.203-20151015213227/@comment-26841482-20151020042808

Because she tortured Seidou. It's pretty much out there. Seidou's personality is really similar to Eto's. It would have been more sensible to assume that Tatara tortured him, but he seemed to protecting Seidou and even taking his side.

Given, Eto tortured Kanae, it's highly likely that she tortured Seidou, too. That's why his personality is similar to the woman's. Remember, Kaneki adopted parts of Yamori's personality after the torture, too.

So, it's not wrong to assume that Seidou knows Eto's true nature. Even someone like Nico, who wasn't high up in Aogiri, seemed to know some obscure facts like the identity of the OEK.