Originally Posted by
Anzaman
Starting character amount depends on amount of players - start alone, you'll only create one character to begin with, play with friend and you both create your own characters, and so on. You can pick up companions very early into the game, so you wont be playing alone for long.
You'd need party of four if you'd want to make whole party of custom characters from beginning. Or once you have completed Act I, you can hire mercenaries as custom character fillers if you don't want origin characters in your party.