Perceived

: Super edgy. Literally no personality outside of liking "hurtin' people and being badass," to quote the Coldsteel the Hedgeheg meme. Or, more rarely, just Pit but evil.
Canon

: Mirror of Pit. Pit is fiercely loyal to Palutena, so Dark Pit is equally passionate about serving none but himself. Pit's super naive and kind of dumb, while Dark Pit is far more savvy and intelligent. However, while Pit is pretty much a pure good guy, Dark Pit is not evil. He's a completely neutral character, who only seeks to accomplish his own goals, but is also willing to ultimately fight the good fight when **** really goes down near the end of Uprising. Dark Pit is also very insecure about his identity as a clone of Pit, which drives his rivalry with and desire to defeat Pit, so he can prove his own superiority to himself.