I always play as the good guy, and this time I want to try something different, but its hard to find motivation.

In the last playthrough I was an Energy Gun specialist, expert in Science and Repair, with an army of robots beside me (Robco Mod), and decided to save the human knowledge by finding lost pre-war books, skill books and lost advanced technologies. I did all this while trying to help all the survivors as much as I could.

But this time I created a Melee and Small Guns specialist, a Scavanger, with the intention of doing evil stuff with him. But I can't find a good reason to explore the wasteland with him. With the last character the purpose was clear... find lost knowledge to save it. But with this guy... I simply can't see how an evil character might find motivation to explore and finish missions.

What reasoning do you use to roleplay an evil character?