Code Geass Idea
This is a "What if Lelouch stayed a prince" story. Yes I know that's been done before. Here it goes:
"That is what it means to be royalty!"
"... I understand... Your Majesty..."
Instead of giving up his claim to the throne, Lelouch retained it. He decided, that his odds of getting revenge on his mothers killer, as well as on the bastard who felt nothing at his mothers death and treated his beloved sister as if she was nothing.
After he left he returned to aries villa and brooded for hours. He decided that he needed allies. He immediately made an alliance with Cornelia, by using logic and his natural charisma to get her to believe that she was assassinated by a brittanian noble. Schneizel offered Lelouch an alliance related to dethroning their father, which Lelouch accepted. Lelouch managed to convince Cornelia to hate their father just as he did (not that is was very hard), and so the three of them united. Shortly after, all of the servants quit. Schneizel replaces all of the staff, except for the head maid (and personal assistant), which he picks out for himself through a short series of interviews.
7 years later (at age 17), Lelouch goes through basic training, and because of his leadership skills and just a little string pulling, was given a command of his own on a different battlefield then Cornelia in the same area. His constant victories got him promoted to the same rank as the Witch of Britannia. His color scheme for himself and his troops being black and gold, as well as the borderline demonic smile when he comes up with the strategy that leads to victory, earned him the moniker "the Black Prince". Despite his nickname he was a very popular war hero just like Cornelia. Throughout his campaign he video chatted with nunnaly who was at aries villa. His head maid also stayed at aries villa.
Lelouch and Cornelia both made sure that their soldiers loyalties were to them first, and the emperor second. This meant that 20% of the millitary would support them. In addition to this, Schneizel estimated that about 25% of the nobility would support him if he took over, as well as another 10% because of Lelouch's support of him. This was still nowhere near enough to take over the empire. To remedy this Lelouch suggests to Cornelia and Schneizel that wile Schneizel gains the rest of the pendragon based nobilities support, Lelouch should be sent to Area 11 to convince the nobility there to support him. They agreed to this because they had very little political support from that area. And so Schneizel pulled some strings and got him installed as Clovis's sub viceroy.
(The rest is up to whoever decides to write this, if anyone does.)