Charlie was the last of his species, the Rhodians. He was rescued by the Twelfth Doctor during a war with Shadow Kin, and taken to Coal Hill Academy posing as a student from Sheffield. (TV: For Tonight We Might Die)
Personality
Charlie was gay. April described him as weird, saying he didn't know anything about pop culture. To her, he'd have to be either alien or Amish. (TV: For Tonight We Might Die)
History
Charlie was born and raised on the planet Rhodia. He was a prince, and ruled over his people for several years with his mother. At one point, the Rhodians went to war with their planet's other race, the Quills. The Quills' freedom fighter was enslaved to serve Charlie and be his protector.
The Shadow Kin attacked and killed every Rhodian and Quill, including Charlie's mother. (TV: For Tonight We Might Die)
Charlie and his servant were then rescued by the Twelfth Doctor, who took them to Coal Hill Academy, where they posed as a student and teacher named Miss Quill from Sheffield.
Miss Quill posed as a teacher while Charlie posed as a student in Year 12.
Charlie asked Matteusz out for the school prom, and they attended it together. (TV: For Tonight We Might Die)
He encountered a dragon monster which ate his headteacher, Mr Armitage. (TV: The Coach with the Dragon Tattoo)