Betrayal
Gibbs hated being lied to. Especially when the person who lied never lied the same way twice.
Liars never kept their stories straight. They couldn't remember what they had said from on story to another.
That's how they catch them.
Gibbs was betrayed by someone he thought he could trust. Someone who had never steered him wrong.
Until now.
He sat and wondered how he could have been steered so wrong by someone.
He always tried to be careful.
Never trusted too easily.
He blamed himself for what went wrong. He had trusted too openly.
It had gotten him killed.