All of the mane are fighting against the Lunar Rebellion, but they have all betrayed the Celestial Empire, including newly winged, Twilight.
They are all fighting for the cause to bring down social status and bring up equality for all races of Equestria.
Elves have ruled above Humans and Avians for centuries. The Gods and Goddesses favored the Elves for their magical ability.
Avians were next on the social list, and as for the humans, they were left at the bottom of the foodchain.
They lacked any magic of any form which gave them the appearance of being insuperior to the other two classes.
Because of this, discrimination played a big role in the land of Equestria. Humans were mostly living in poverty and weren't aloud the same privileges as the other three races.
The mane six, coming from completely different backgrounds, band together to stop the racial war against Equestria's people.
The racial war was commonly mistaken for the Lunar Rebellion. Because of this, those who were against social class were seen as treasonous to the Celestial Empire and were prosecuted.
Leaving the Mane six with a big "WANTED" sign.

Hope you enjoy.