Gunslinger Girl/Nightmare Fuel

"Rico: "I am sorry." (fires)"
 * Any number of Creepy Child moments.
 * Rico smiling because she's just remembered the correct thing to say in an awkward social situation as she points her silenced pistol at an innocent boy who's seen her during an assassination.

"Henrietta: "How can I kill myself when you're this wonderful, Jose?""
 * You just had to include that didn't you. Just the mental picture of that during Rico's Character Song (La Principessa del Regno del Sole ~Mujaki na O-hime-sama~) brought me to tears. Seeing it animated just made it worse.
 * Rico's angelic smile as she goes to beat information out of a terrorist.
 * Henrietta's implied threat in reenacting

""Hello roommate, neighbour. I am home.""
 * And then there's the moment where.
 * Henrietta leaves Rico and Triela in their dorm and comes back a reconditioned zombie.