Schneizel el Britannia

"Cornelia, what is that people truly want? Starvation and poverty? Discrimination and corruption? War and terrorism? They want the problems that are flooding the world to go away forever. People can't understand each other under these situations at all."

- Schneizel to his sister,Princess Cornelia "I wonder, Lelouch...do you really think you can defeat me, because if you do, you're at the end of your path. A man who has not mastered the use of the mask cannot prevail."

- Schneizel to his younger brother, Lelouch Schneizel el Britannia was one of the primary antagonists  of anime and manga series, Code Geass, alongside his father, Charles zi Britannia.

Personality
Throughout the vast majority of the series, Schneizel appeared to be a compaassionate, concerned, and yet endlessly manipulative individual and expert strategist, whose valor, tactics, and honor made him greatly respected by his comrades and subjects.

In the final 3 episodes of the second season, his true personality finally comes to light, as he is shown to be exceptionally power hungry and somewhat unhinged, and willing to kill anyone, even sacrifice the lives of tens of millions of innocent people, if it furthers his objecive of world domination. His cruelty and manipulations were shown to rival even those of his father.

Season 1
He first appeared as a meaningful villain who eventually let Suzaku go free of his charges of insubordination. Later, he is shocked by Euphemia massacring the Japanese and suspects that something is making her do this.

Season 2
He eventually discovers Zero's true identity as Lelouch vi Britannia by having soldiers follow Suzaku and try to make it look like he sold him out. And thanks to using his Geass on Guilford, Schneizel confirms it. In the battle of Tokyo Settlement, he has planned on having Suzaku use the F.L.E.I.J.A. bomb just in case the Geass command "Live" activates when the likes of Lelouch and Kallen try to get him killed. This plan succeed.

Next, he requested a meeting with the Black Knights under the condition that Zero himself will be not attending. This is the point where he tells them about his true identity, Geass, and the F.L.E.I.J.A. with some manipulative evidence. Ohgi and Viletta support him, saying this is all true. This leads to them betraying Zero, but the former requested to get Japan otherwise he'll go after Schneizel.

It wasn't until the 23rd episode of the series (when Lelouch became the emperor of the Holy Britannian Empire), that Schneizel revealed how dark and twisted his personality was. After taking charge of the Black Knights with Cornelia and Diethard by his side, Schneizel (wishing to "free" the empire's capital city Pendragon from Lelousch's rule) used the F.L.E.I.J.A. system to obiterate the city killing tens of millions of people. To Lelouch, he eventually revealed that he hid Nunnally from him the entire time, and was able to turn Nunnaly against her brother. Next, told Cornelia of his plan to seize control of the world back from Lelouch by using the Democles satellite weapon to destroy every capital city on Earth and to "become a god". When Cornelia protested, he had her shot.

He then went to battle against Lelouch, with each of the pair's fleets masterfully commanded by th other in a chess-like battle for power. In the end, Lelouch used a securadite-based weapon in the Mount Fuji mines to trigger a volcanic eruption which destroyed vast swathes of Schneizel's fleet (as well as many of his own soldiers).

Using the Black Knights as expendable pawns, he had a hidden fleet of them attack Leluch's ship the Avalon from behind, where they caused enough damage to begin sinking it. Lelouch left the Avalon and led a strike team of Knightmares against the Democles. In their attack, Schnized had Nunally launch a F.L.E.I.J.A. warhead at them, but Suzaku shot a disruptor at it, stopping it from detonating.

When Lelouch and his team infiltrated the Democles, Schneizel announced that he planned to evacuate th satellite and destroy it with a F.L.E.I.J.A. warhead, killing Lelouch and strike team, and allowing him (Schneizel) to seize control of the empire.

Lelouch appeared on the screen of Schneizel's escape shuttle, distracting with a video message, bofore appearing to Schneizel and using his Geass power to force Schneizel to be solely obedient to Zero. He then ordered Schneizel to kill Diethard.

After Suzaku became the new Zero and killed Lelouch by impaling him through the chest with a longsword, Schneizel entered service under Suzaku, and Nunnaly became the new Empress of Britannia.