Danzo and sarutobi fight over naruto's future, and Danzo figures out that Naruto is the 4th's son. He tries to leverage that by blackmailing Sarutobi, but sarutobi calls his bluff. The word gets out to Iwa, and assassins come for naruto. Danzo is forced to flee when Sarutobi comes after him, but the damage is done.
Naruto is then subject to frequent assassination attempts. The Konoha ninja, as a result of Danzo's actions, learn Naruto is the 4th's kid, but are forbidden to tell him. Since he is no longer protected by anonymity, he is given one off trainings and hint as he is semi protected/adopted by the Konoha ninja corps and Kakashi in particular.
As a result, Naruto is still inquisitive and outgoing, but he's less in your face and idiotic. Having learned that standing out makes you a target, he blends in better, but still pranks as it is good practice at being a ninja. The frequent near death experiences has made him less Pollyanna, and though aware of the Kyuubi (Sarutobi is forced to tell him), he isn't aware of his father or why the Iwa ninja are out to get him.
Civilian reaction is hatred, ninja are ambivalent to pro, but there is a fear regarding naruto as each assassination attempt leads to the release of Kyuubi's chakra in the middle of town. Everyone has experienced it, and only the older ninja know what it is but refuse to say anything about it due to statute.
With Danzo gone, the Uchiha massacre happens, but rather than every last uchiha, only the adults and children over the age of 11 are killed.