The ANBU member looked at the demon child with hate filled eyes, it had killed many of his comrades, friends and family in it's rampage over a decade ago. Several of the passing villagers cast worried glances at the Uchiha and pink-haired girl that were accompanying the demon in human clothing, others were leveling cold, angry, hate-filled stares at the demon brat. Seeing them look at it like that made the ANBU's insides boil with rage; it was their fault, all their fault! It was their fault that the demon was in control, it was their fault that the host was dead; they are directly responsible for Naruto Uzumaki's death.
He had helped the Fourth study the seal, and together they had found out that the seal feeds on emotions; strengthened by love and weakened by hate and rage. The Fourth wanted the boy to be treated as a hero, to be filled with love in order to strengthen the seal, but only a few had honored his wishes.
The seal began weakening when the boy was four. The demon began affecting the boy's mind by the time he was eight, turning him evil and volatile. The boy never reached nine; the demon had killed him and overtaken his body. He took solace in the fact that the Nine-Tails was still trapped in the body of a child, but it was only a matter of time before the seal would completely shatter, and the demon will attack them once again.
The Hokage had issued ANBU to guard him until he became a Genin, and he was one of those who were often sent. For the first eight years, he saw it as protecting the boy from the villagers, afterwards, he saw it as protecting the villagers from it. He had tried to explain it to the Hokage, but the Third wasn't willing to listen to reason, so he and several other ANBU members had taken it upon themselves to keep an eye on it whenever he wasn't with Kakashi Hatake.
He knew that the fox was biding his time, and was doing it well. He guessed that some of the boy's soul remained, and the demon is using it to create a mask. Eventually the fox will escape, and they'll be forced to seal it within another child, that time, he will tell the villagers how they had killed Naruto Uzumaki, the next time, they won't make the same mistake.
His only regret is that Naruto had to die for it, and that others are bound to follow.
