Sanosuke could feel the blood itself coursing through his veins as he was about to erupt. His mother was dead, killed in front of him by a man called Uchiha Aiosuke. A very persuasive man who up until now thought that he was for real. Now he was a dead man. But Sanosuke had to think this through. He was over confident and that could be his downfall. Sanosuke would make sure of it. His father when he heard his mother scream out came out of the house running and he too was placed under a paralyzing genjutsu and was beheaded by Aoisuke before he could activate his own Mangekyou Sharingan.
Sanosuke knew for sure that something was growing within him. He could not yet explain it but yes it was definately there. An unfathomable power that even he was unaware of. Suddenly, as he saw his father's decapitated body hit the floor, he could not explain it, but the scenery changed from one of horror to one of a vacant place, cold and dark with several stone constructs, all perfect in every way and then he passed out as he had gained his Mangekyou Sharingan; still unbeknownst to him.