The being who called himself the embodiment of Madara's will had said that Madara's Reincarnation would one day be born into the Uchiha Clan and possess tremendous potential. He therefore wanted Uchiha Setsuna to find Madara's Reincarnation. Although Uchiha Setsuna could not tell which child was Madara reborn, the black shadow called Zetsu could. For some unknown reason, however, Zetsu could not enter Konoha Ninja Village himself, so Uchiha Setsuna had to find a way for Zetsu to see the children outside the village.
Fortunately, no complicated secret technique or ritual was needed. Zetsu only needed a glance, so Uchiha Setsuna simply had to take the children for a stroll near the village gates. First, though, he needed a way to find out about the clan's newborns.
To that end, Uchiha Setsuna began showing concern for the clan. Even Kagami Uchiha believed he had truly turned over a new leaf, but no one knew that Uchiha Setsuna was actually searching for Madara's Reincarnation. After working at it for some time, Uchiha Setsuna successfully built good relationships with families in the clan that had newborns, then used various excuses to have them bring their children somewhere Zetsu could observe them.
Zetsu subsequently determined that Tetsuya Uchiha's son, Ken, was Madara's Reincarnation. Uchiha Setsuna therefore began approaching Tetsuya Uchiha, becoming his closest friend through his "sincere" treatment of him. Naturally, this allowed him to see Ken.
Because Ken was Madara Uchiha's Reincarnation, Uchiha Setsuna had extremely high expectations of him. He believed Ken would one day replace Kagami Uchiha as their leader and restore the Uchiha Clan to what it had once been, rather than letting it stray further down its current misguided path.
"I really hope I can see Ken all grown up soon. I wonder what sort of man he'll