Impossible Trinity
Impossible Trinity is a PlayStation 3 trophy, and an Xbox 360 and PC achievement awarded to the player after completion of mission Museum Piece in Grand Theft Auto IV.
The achievement is named as such because during this mission all three main characters of the 3 different episodes (Niko Bellic of GTA IV, Johnny Klebitz of The Lost and Damned, and Luis Lopez of The Ballad of Gay Tony) are brought together at the same place and time in an amazing coincidence.
The Impossible Trinity achievement is absent in The Lost and Damned, but returns in the The Ballad of Gay Tony with a different name: "Diamonds Forever".