In the shadow of heroes - Nicholas Bowling

The newest novel from the critically-acclaimed author of WITCHBORN
...

Fourteen-year-old Cadmus has been scholar
Tullus's slave since he was a baby - his master is the only family
he knows. But when Tullus disappears and a taciturn slave called
Tog - formerly a British princess - arrives with a secret message,
Cadmus's life is turned upside down. The pair follow a trail
that leads to Emperor Nero himself, and his crazed determination
to possess the Golden Fleece of Greek mythology. This madcap quest
will push Cadmus to the edge of the Roman Empire - and reveal unexpected
truths about his past ...