Two Faced Trophy
Witness both Songbird's endingsMISSABLE
If you know about this trophy going in, you can get the Platinum in 1.5 playthroughs instead of 2 full ones.
The first step of this trophy involves the quiz with Alonso (Interview Jeopardy ). Make sure you get all the questions correct - see that trophy for the answers.
The second step (and where you want to make a separate save before making decisions) happens after returning from meeting Leet and entering MINOS for the first time. You will be in possession of both a photograph and a plushy. Assuming you aced the quiz with Alonso, then the two Songbird endings come down to whether you give her these two items or not.
Whatever you choose for your first playthrough, finish the game. Once you've finished it, reload the save I told you to make, then choose the opposite action. You should notice that Songbird's conversation with you at the monopod is different than the first time around. Play through the game until you deal with her and Alonso at the City Walls, then this trophy will unlock.