A specific build doesn't come to mind, I guess anything could do really, it's more so the "what you do" side of it that makes this idea stand out. With that said, I am here to propose a roleplaying idea of, The [censored]. Join literally all of the guilds and getting into their questline as far as you want and then betray them (kill the entire guild if possible), save a prisoner / wanderer being attacked by a bandit on the streets and then kill them for whatever loot they might have on them, slay the annoying beggers that practically demand for your gold. Take a side in the Civil War and betray! You have no allies, only caring for yourself, you realize you're on your own in this world and must make the most of it, taking advantage of just about whatever situation you can and abuse the populace. To make it even more fun, play on a higher difficulty setting.