Idea: There was a reason that no Uchiha made Hokage despite the fact that a sizable number of them were in the Nidaime's teaching line.
It had been the month after he was named Hokage that he'd found the hidden file vault that had survived three wars and Pein's destruction of Konoha. It had been while he had been exploring that he found yet another reason to hate Shimura Danzo.
He'd known for a while that the Uchiha massacre had been a fucking set up. Suspicion would not have fallen upon the clan so strongly had Danzo not detained Fugaku and his wife on the night of the Kyuubi's attack, and had he not set people whispering about the village.
But this...
This...
One of the reasons that the diplomatic talks between the old man Sandaime and Fugaku had fallen through had been over the fact that there seemed to be no hope of there being a Uchiha Hokage unless there were a coup.
Prescident for the selection of Hokage had been set when the Nidaime had selected one of his students for the position. The fact that the top two candidates for Yondaime had been one of the Sandaime's students and a student of another of the Sandaime's students cemented this into tradition. By the time that Tsunade became Godaime, it was pretty much established fact that future Hokages would come from the Nidaime's teaching line. By then however, it was far too late...Danzo had gotten the Uchiha to destroy themselves.
It had been while he'd been looking through some old records, curious about his father's teammates that Naruto had found evidence of one of Danzo's pre-massacre plots.
After digging through the records and finding out about the Genin team his father had been on, he had dug up the records of Orochimaru's students out of idle curiosity. Something immediately began to stand out. Once is interesting, twice a coincidence, and three times, the beginning of a pattern. The pattern he'd unearthed was somewhat disturbing.
Going back from himself, the Genin team he'd been on had contained the "Last Loyal Uchiha" who had been neither. His sensei Kakashi's team had also contained a Uchiha, one who had been rather popular with the villagers, and had died far too young. Kakashi's sensei Minato's team had a Uchiha on it who had also died young, Minato's sensei Jiraiya's team did not have a Uchiha on it, but his teammate Orochimaru's first Genin team along with having the ill fated Nawaki had also contained a Uchiha who had died young. Team Tobirama had not contained any Uchiha, but two of his three students had trained teams that each contained a Uchiha who oddly enough survived into their early twenties rather than their early teens.
Going by the line of descent from teacher to student, there should have been a Uchiha candidate for Yondaime and Godaime after him or her.
The reason there wasn't, Danzo.