It is the first thing Neji does as Head. It is his first act and use of his power when he is made the Head of the Clan.
Hinata dutifully drops her eyes and accepts the decision with barely a word.
Hiashi wants to fight it but it is no longer within his authority and Neji has proved to be perfectly reliable in his decisions – except for this: this, Hiashi is sure, is madness.
Hanabi wants to rage and scream and – she does. She yells and kicks and fights. The obedient daughter for once rebels and she wants to know; why, why one and not the other.
Why her and no one else.
But Neji, the rest of the Clan and the Council is convinced, is the way towards the future. He has the sight and the blood is thick in his veins. For his guidance, they are willing to let this transgression pass, when pressed. And they are pressed.
Neji breaks no arguments or compromise; neither does he share his reasons. This, he says, is the price he asks.
It's painful and it hurts and burns and it will last until forever as the seal is etched onto Hinata's forehead. She closes her eyes and accepts the pain and the burden.
This is the last seal to that will ever be done.
And they don't understand but Hinata does. She understands him better than anyone, she always has. She sees the light in his eyes when he looks at her, and her father is right, it is madness.
Neji was caged, and even though now he has been given the key, he cannot forgive those that had restricted and confined him for so long. Some part of him deep down will never totally forgive those who had taken his freedom away from him, no matter how temporarily. The remnants of the seal will always stay with him.
But that doesn't have anything to do with this decision, not really. And some might say he was responding erratically to the fear or suddenly whelming of his newfound freedom – but it isn't that at all.
It isn't his freedom that he fears: it's hers.
He's scared that now there are no bonds tying her down she will fly away one day; away from there, away from them.
He desires to put her in a cage – his. He wants her next to him like it has always been. He wants the promise/pledge/guarantee that she would always be by his side somehow.
And it is madness, a deep chilling madness.
Hinata knows. More than anything, more than being caged and limited and confined and being unable to reach the top of his potential, Neji fears being alone. He never wants to be left behind and alone again.
If Neji was a bird and the seal a cage then if Hinata had wings and the cage could not hold her because it has already been broken, he would – eventually will – clip her wings.