Other notes:

- "Dark Knight" - I got this pretty easily by roughing up both suspects in 1st interrogation once, all suspects in 2nd interrogation once, using the harsh/threatening options, and picking the unprofessional/cruel dialogue options with other characters. I don't believe the guide is correct to say that all you need to do is torture everyone in the 2nd interrogation until they pass out; in my experience, that only gets you fired.

- "Cure the Plague" - Unlike others in this thread, I couldn't get this ending no matter how I replayed episodes 9 and 10. What I ultimately did was start a new game wherein I recruited the 4th task member, agreed with them about killing Lee/Reed/Bennet extra-judicially, got the Messiah trait, and pressured all three suspects heavily.

Some notes:

- "Restart an interrogation ten times" means you must FAIL an interrogation and then try again when prompted; restarting from the menu doesn't count. Tasering the suspects in the 2nd interrogation until they pass out is a quick way to get this.

- "Accuse the same innocent 100 times" is best done in the 1st interrogation, as there is no timer and you can spam-click the accusatory option. A timed investigation will end before you can make 100 accusations, as you can't restart the level to cumulatively grind them over multiple attempts.

- I got "Evolve or die" by replaying episode 10 and making specific choices that maximized empathy with Bennett and kept it to a minimum with Lee and Reed (in narrative mode).

Haven't been able to get "Cure for the Plague" yet despite replaying episode 9 and 10 and putting high pressure on Lee/Reed/Bennett. I also don't have the Messiah or Mad Genius trait, or the 4th team member.

I got Cure for the Plague last-minute by choosing the messiah personality trait, which gave me the ending to execute them all. I didn't have the fourth team member or maximum mental instability.

Maybe the mental instability is related to the Mad Genius memory badge? It's the one I chose and got the achievement. Also played as a pacifist.

I'm back here and I'd like to say that I followed steps provided by CamAddLess and got Evolve or Die and Cure for the Plague by only replaying interrogations 9 and 10, so yep, it can be done no matter what you do throughout the game! I had that guy on my team though and agreed with killing the leaders. But it seems like it's not mandatory, and I was otherwise a 100% pacifist during the whole game.
I stil don't really get what that mental instability thing is because I'd rather not stick with being the bad cop while playing but making all three suspects in 2nd interrogation passing out got me the cuckoo's nest and hate your guts achievement in no time.

I think the icon of the "Hate Your Guts" achievement might be wrong: you used the one from "One the Subject of Delusions" instead. No big deal of course. Nice guide!

Sorry for the long intro in the previous comment but here's how I finally unlocked the ending tied to the Cure for the Plague achievement:

On the same save profile, I went back to Episode 9 and this time around, I set my sights on Anaba Lee. Empathy didn't seem to work with her so I had to put quite a lot of pressure on her before she even agreed to talk about the Front in a theoretical way. And then in Episode 10 I continued this strategy with everyone, increasing their stress levels first and foremost, and only empathizing enough for them to turn on each other. And much to my surprise, I got the option to summarily execute the whole lot. And I did all that WITHOUT resorting to violence (which you cannot use in the final interrogation either way).

So it seems that increasing everyone's stress levels during the last two episodes was enough to trigger that ending.

I've just unlocked Cure for the Plague achievement and I'd like to leave my insight here in hopes it'll prove helpful to others.

I did NOT have either the badge nor the team member mentioned in the guide. Nor was I mentally unstable, I don't think. I actually played by the book for the most part, not once resorting to any enhanced interrogation techniques, mostly empathizing with the suspects and only ocassionally putting some stress on them, but only psychologically, as the circumstances demanded.

During my first blind playthrough I successfuly convinced Damascus Reed to give up the two remaining leaders by first employing an empathetic approach to his cause and then putting about equal pressure on him while he was theorizing about the Front. Towards the end I could choose between sending all three of them to trial, releasing Reed or releasing Bennet.

One other note on Cure for the Plague: You get the option as one of your three choices after ending the interviews peacefully. In other words, there's no way to shut off the tape recorder in the final interview, no matter what prep you do.

I played the path of the empath, taking Double Agent, and never turning off the tape recorder throughout the game.

I just got Evolve or Die anyway: As someone mentioned earlier, you just make sure you connect with Bennett and not the other two. The other endings were also available from this some playthrough just by replaying the final interrogation. Therefore it may not (perhaps does not at all) depend on what you do before the final interrogation.