it cant be sakon/ukon cuz kiba knew they were coming because of the blood trail before he discovered the scent. like everyone said its prolly not a leaf shinobi or else kiba wouldnt have been scared and leave. i doubt its orochimaru cuz he doesnt know his scent cuz he was knocked by kabuto. could be shikamaru and tayuya. gaara and co. theory isnt too farfetched cuz kiba knows their smell and hes afraid of gaara.