Will I be able to play as Psycho with a friends who does not have Psycho Pack?
I am considering buying Psycho Pack and playing as Psycho with my brother. However, I need to know whether this is possible without him also buying this DLC.
So the situation: I have Psycho Pack DLC, other player does not, can I join their game with Krieg (psycho)?
Yes, you will be able to play with your brother even though he does not have the Psycho Pack DLC.
The DLC only unlocks Psycho as a playable character, the files needed to have him in a multiplayer game are already in the game, regardless if the DLC is purchased or not.