The thing about Tony and Ziva isn’t just that they have history, which they do. It isn’t even that they fit well together and complement each other, even though there’s also that. Or that at one point, they decided they wanted to be each other’s family, officially. With rings and all. It’s that at every hard point in their lives, at times when perhaps the safer option would have been to give up, they’ve chosen each other. They just have never found a way to make that stick in the romantic sense. But the choice, over and over again, cannot be discounted.
Even when they couldn't make it stick romantically, they are there for each other. One could say it's because of Tali, but even if Tali never existed, they would be there for each other as soon as they knew the other needed help. They both care *so much* about the other even without romantic feelings added in. The lengths they'd go to for each other, *HAVE* gone to for each other, speaks to an indelible, unbreakable bond, that rooted in the grounds of possibly the greatest friendship either one ever had.
