Vampire: The Masquerade - Coteries of New York (EP)

*MISSABLE*: The game takes place over 17 Nights, but only half are available for side-quests. On the 13th night, your final quest will begin and you will have only one more opportunity to do one segment of any of the selectable quests. As each questline requires 4 meetings to complete, you'll need to keep this in mind or you'll have to start all over again in a new playthrough.

This trophy will pop at the end of your fourth and final meeting with Agathon.
 

In your third visit with him, you will meet his grandmother. Next time, your fourth, you will join him and finally confront Juno in her own haven. Once there, after a short dialogue, you'll finally manage to procure the notes, whether by force, intimidation, persuasion, etc, whichever you choose. When you return to Aisling with the notes in hand, that concludes Agathon's quest line and you'll earn this trophy.