There is no more absolute proof that something had existed than the void left in its absence. The proof of life is not birth; it is death. Absence is the first absolute Ziva learns. She learns the feel of a body becoming a corpse in her hands; the sight before her eyes. Each death she chooses to bring about pushes further away the memory of the she hadn't: the memory of the torn, bleeding flesh that used to be her sister.
She'd had a sister once. A brother, too. In the cold of vacuum, it matters less which she chose.
It is the girl Ziva had looked straight at before she committed murder by suicide. It is the man who was not a physician. It is Ziva's word to her father and Ari's word to her. It is trust offered (tacitly or explicitly) and then denied, any faith put in it proven false. It rings better in Hebrew, emun, emet and emuna. To Ziva, that's reason to choose other languages.
She had prayed God, full of mercy over the body of the brother who had betrayed her and whom she had betrayed in turn, but she did not say amen.
Whenever Tony hums Chad Gadya under his breath Ziva wants to scream or laugh. It is a vicious circle, Chad Gadya, and the end is only ever one, the same as always.
She had been betrayed by a father she would have betrayed for a brother who would have betrayed her. She had betrayed Ari, who had betrayed their father, who had betrayed Ari's mother. Only the first link in the chain mattered, only the first was a choice. The others merely follow.
Tony doesn't know to mean it, but what Ziva hears is the promise of her being next.
She believes in betrayal like she believes in death and consequences. These alone prove true, time and again. The world is too arbitrary for anything else to be relied upon. Ziva smiles politely at claims that the world is either cruel or kind; she knows better than that.
She knows, too, that the chaos can be kept at bay. She knows that some people survive longer, do more betraying than being betrayed. The good manipulate patterns and the better create them. She would not call herself 'better', yet, but every day is further proof that she is competent at living.
It takes effort, living. It would be easy to slip and easier still to put a bullet in her head. Each morning she gets out of bed and every night she puts the gun under her pillow proves that she believes in something more.
She memorizes the outline of it religiously, lest the void loses its shape. To forget this is to have herself forgotten; to forget this would be death.
She bears the pain and the name long after the thing itself is forgotten, and when it is returned it takes Ziva time to remember that this is love.