Disclaimer: I don't own Naruto.
Shizune may be more dangerous than her mistress.
Tsunade always draws attention to herself. She is blonde and beautiful; with a charismatic, thrumming presence, she dominates whatever room she enters, even when the attention isn't all on her. She draws eyes, attracts attention.
Hardly anyone ever notices that there is someone at her heels.
Shizune is always one step behind Tsunade. Not in front of, not at her side, but behind, head bowed, silent.
She is pale-skinned, with raven black hair that barely reaches her chin and wide coal black eyes framed with long sooty lashes. No one ever notices how bright and keen her eyes are, because they are always modestly downcast.
She is a pretty woman, beautiful even, but as she is, overshadowed by Tsunade, no one will ever see it. Dressed in dark, loose-fitting kimonos and even darker charcoal black cloaks, she resembles nothing so much as a raven or better yet a crow, small, black and unimportant. A carrion bird, harbinger of death, yet overlooked. Wherever Tsunade is, Shizune is utterly invisible.
This is how she likes it.
No one guesses that small ivory hands thick with calluses are deft and clever with toxins to make the blood burn and the heart stop in mid-motion without a sound.
No one guesses that thin arms sheathed in black linen, their skin patched with calluses and scars, can put the force behind hands that can, with cool, calculated brutality, inflict precise strokes from kunai, senbon, shuriken, weapons laced with and dripping odorless toxin. No unsuspecting victim ever suspects that Shizune is anything but a servant.
Those who notice her do not remember. They see a tall woman made strangely short by her stance, pacing down a hall with her head bowed like a monk's, the cloak rustling behind her. They hear her almost shuffling walk, see her hunched shoulders and lowered eyes. They dismiss her as subservient, nonthreatening, harmless. They almost expect to see glossy black feathers flutter away from her cloak as she flies down the hall.
Shizune always walks that way after killing someone.
The raven hides deadliness behind a drab tapestry of black feathers. The keenness of its talons and the lethality of its curved beak are overlooked in favor of the obvious threat of the hawk and the eagle.
It is the raven that scores its kill. And no one knows that Shizune, though she seems to be a crow, is in fact a raven, waiting to strike.
Tsunade's attacks are obvious and devastating. There is no subtlety in the fists that bring down walls and level cities.
In Shizune's methods of dealing out death there is subtlety. She is silent, quiet, overlooked, a thief in the night. Her attacks, though invisible, wreak more havoc on the internal system than Tsunade's do on the external.
Everyone notices Tsunade. No one notices Shizune.
This is where all the danger lies.
Good? Bad? Appropriate or not? Shizune is one of my favorite characters, and the comparison seems to fit.