The second 'optional' (or hidden) character in the game, Vincent can also join your party during any disc. You'll need the gold key from the
safe in Nivelheim's Shin-Ra Mansion (see below if you don't know how to open it). Go down to the pink cavern leading to Sephiroth's library
(it's in the Shin-Ra Mansion, the entrance is in the stone wall in the eastern wing).
Remember the door to the crypt you couldn't get through? You can now enter it. Stand at the foot of the purple coffin and hit O. The lid
will fly off and Vincent will talk to you. hoose the bottom reply when he asks you a question. When the coffin closes, press O again. Choose the second (bottom) reply when Vincent poses another question, and you
can name him. Then, try to leave the cavern and he'll join you. Vincent can join you from the first time you reach Nivelheim onwards (but not
during Cloud's flashback).
THE SAFE IN NIBELHEIM
What most people forget when trying to open the safe is that it's just like a real combination lock...so you have to go in more than one
direction when inputting the numbers. Furthermore, unless you're fast enough, you'll run out of time if you try any other combination.
The code is:
RIGHT TO 36, LEFT TO 10, RIGHT TO 59, RIGHT TO 97
This means that you hold right and scroll through the numbers, then hold left until you reach 10, then hold right for the last two numbers. Don't forget to press O to verify each entry. When the safe opens, a Summon Materia (Odin) pops out, and you are assaulted by a big goon (how'd he fit into that little safe?)