Co-Op With A Friend
New to Bloodborne is the ability to link up with friends. It's not as easy as sending an invite, but once you know how it works, it's easy enough to battle the darkness with someone you know.
Basically, the game accomplishes matchmaking through a password system. Hit option on your controller, and head over to the settings section on the right side:
Scroll down to network:
Change your region from "local" to "worldwide."
Now, set a password. Important: both players must use the same password for this to work!
Once you've done that, one player rings the Beckoning Bell, while the other player rings the Small Resonant Bell. If you're hanging out in the same area, after a few seconds (and sometimes minutes, so be patient) of waiting, the game will find a way to bring you across the void and...
Voila! You can now slaughter beasts with someone you know. If you defeat a boss, the person invited into the world will be banished, and you'll have to start the process all over again.
Heads-up: if you're still having trouble connecting with a friend, it's possible your levels are too far apart. When asked, Sony recommended players were within 10 levels of one another.