Sakon is one of the the ninjas of the Sound Four, the elite body guards of Orochimaru. He is also one of the strongest of the four sound ninjas. He is a twisted one and enjoys bad mouthing the opposition. Although he talks a lot of trash, he can back it up. His power is unbelievable and he is very fast. Sakon has amazing power and speed but these are not the only things he has at his disposal.
Sakon is a very noticeable ninja. From his back one can see what looks like another body which is just hanging from his back. This is his brother Ukon, who is his older sibling. He stays asleep in Sakon's body until he is activated by the level 2 Cursed Seal. When he is activated, he takes the same shape as all the other Sound Four when they are activated. They appear to be demons.
Sakon has a 2 to 1 advantage in fights, and when the need arises, he always has a partner ready. Sakon has an ability in the second stage of the Cursed Seal, which enables him to manipulate cells and proteins which allows him to 'merge' with the opponent and kill them. This is his special attack but it has a flaw. Because they are merged if the target should die or kill themselves then the one who has merged with them will die as well.
Sakon and Ukon work as a team and because of this they are more reliant on each other. When split up, they may be able to handle a 1-1 fight for a while, but when they have to face a strong opponent, this is their weak point.
Other than that, little is known about Sakon and Ukon. What their bloodline limit is? Did their techniques came from Orochimaru? Though these things are not yet known, he appears to be a scary, fierce, and strong opponent who will slaughter anyone who interrupt his mission.
When the Sound Four was returning to Orochimaru together with Sasuke, Kiba was found in a battle against Sakon and Ukon. Kiba couldn't, naturally, deal with both of them and they toyed around with him. That's when Kankurou showed up and, in the end, used his Black Secret Technique Machine One Shot on Sakon and Ukon, killing them.