"As for what I want... can never be given. Instead, I've opted for an alternative. Peace on Earth." -Zero
Zero is the protagonist, and anti-hero, of the fanfiction Kristallnacht. He is the leader of an organization known as the Black Militia, a group of unknown origin. His true identity remains a mystery, but it is speculated that he has some sort of connection with the Britannian royal family.
Zero's history remains a total mystery left to mere guesswork. Some people speculate that he was a Britannian soldier, perhaps highly regarded, before being left for dead after a mission gone wrong. Others believe he was simple man before his life spiraled into tragedy at the hands of Britannia, hence his rage. A few believe that he might even possibly be the Britannian prince who was exiled, and left bitter and angry, wants to destroy his former home. Regardless, Zero is seen as a powerful and charismatic military leader, leading a large organization with ties overseas.
The first known record of Zero appearing was three years prior to the events of the story. Originally leading a small band of mercenaries in the European Union, he quickly overwhelmed the Britannian forces with strategic maneuvers and intensive firepower. Soon afterward, the band he led grew in number, which would later come to him taking over a military base stationed near the EU-Britannian border. Within a year, Zero had taken over one-third of the Britannian territory in the EU, which contributed to the European forces' victory.
The second known, and perhaps the most infamous, records of his existence was in the Chinese Federation. Though accounts vary, Zero had apparently aided in stopping an attempted assassination of Empress Tianzi. He was recorded to have several accomplacies, all of which ranged from Chinese to Britannians and even, allegedly, Europeans. Through the varied accounts, all agreed that he helped in destroying the apparent rebel faction. Like before, he disappeared like a ghost, leaving little traces of his being there.
In the Black Militia, Zero is seen as a powerful military figure, respected, feared, and awed by many. Due to his sheer brutality towards the Britannians, a few of his own men have come to call him the "Demon Soldier," which he earned fittingly well as he mercilessly executed any foolish enough to face them. That being said, he welcomes any who see the true nature of the world, or someone who understand his views, regardless of nationality. Naturally, he treats traitors with untold harshness and brutality. He has even executed some of his own men himself.
Overall, Zero is regarded as the most formidable force Britannia has ever seen, and a man with a brutal vendetta.
Zero has displayed several characteristics of his personality through out the story, most notably his absolute hatred of the Holy Britannian Empire, and by extension, the Royal Family. He is a spiteful individual who wants nothing more than to wipe out the nation off the face of the man, even if it meant starting a war. He will do whatever it takes to achieve victory, even if it means killing innocent bystanders. That being said, he wishes to avoid needless deaths, saying that a precious person he held dear at one point wouldn't want him to become a heartless monster, though he continues to rebuke this, saying that without them here, he has lost all sense of self of what used to be his humanity.
He shows some compassion to his soldiers, saying that they should mourn their losses whenever they could, and to continue on. He also welcomes any person of nationality into their group, though he does not take betrayal kindly, and will personally eliminate anyone who defects. Because he leads such a large group, he must often take action and lead his group accordingly as a commander should, and therefore, puts the needs of his men above his own needs.
His apparent, driving motivation is his precious person, whom he has mentioned on several occassions. Many people have speculated who this might be, but C.C., who granted him his Geass, claims that it was his younger sister, who died during the invasion of Japan, as well as his best friend. Losing two people so very close to him was what molded him into the man he is now, and claims that Britannia must be eliminated by any means necessary, even becoming the enemy of the world if need be.