While the slaves appear submissive under the watchful eyes of The Sovereign Wing (the Gale Guards), a massive, continent-spanning network of secret societies operates right under the aristocrats' noses.
The Rhythm Codes: Slaves are forbidden from speaking, but they have developed a secret communication system using rhythmic work noises. The rhythmic clanging of miner picks, the chopping of woodcutters, and the sweeping of brooms are actually complex messages coordinating supply lines for the Brass Undertow rebels.
The Smuggled Spark: Slaves working in the Sail-Weaver’s Loft and the Anchor Markets secretly sabotage materials, creating micro-fractures in airship keels or hiding stolen skystones in shipments bound for the slums to help build rebel weaponry.