Shadows are important with this fella, so i thought i'd look up the imagery associated with the shadow. ^_^

Shadows with Light are considered as the Yin and Yang and are typically referred to the human soul. Shadows are also considered "dark entities with a nature all of their own". They are also said to be the unconscious layers of the personality that are used in the real world by individualizing oneself.

Well, Shikamaru is definently an individual. ^_^ I'm to lazy to really analyze this and actually i'm really tired because it's eleven ^_^ To me that's late! Oh, but i should add that in Teutonic Myths the shadow world is full of treachorous (and generally intelligient) creatures. ^_^ He's not exactly treachorous but he's not exactly loyal either. ^_^;;