Sathya is a friend and apprentice of Anna Fang . She comes from India, from a background of poverty. She appears in all of the books except Infernal Devices . In Mortal Engines , the first book, Anna introduces her to Tom and Hester in Airhaven at the inn The Gasbag and Gondola.
A die hard Anti-Tractionist, Sathya is at first highly untrusting of Tom and Hester, and is highly protective of Anna. She hates traction cities and often urges Anna to be aggressive rather than stop and think at times.
Despite being a little bit hot-headed, she is a good companion to Anna Fang and eventually gets along with Tom and Hester.
Sathya's hate of tractionism comes from her childhood; she grew up in a nomadic village that lived in the track marks of traction cities, and were always poor and starving. Eventually she managed to 'escape' the village and make it to Shan Guo, where she proved her tactical and combat skill.
She was only still a teenager when Anna Fang died, and in late twenties when the Green Storm siezed control.
Outcast to a remote part of the largest mountain in Shan Guo, Sathya became a hermit, although supplies were given to her by the nearby village in the foothills about once a month.
Here she raised animals and - intially - trained herself for combat on a daily basis. However, as she got older her anger wore out and she now appreciated her exile; the other option was execution.
The Stalker Fang found Sathya as an old woman, and regained most of her previous personality when around Sathya. Fishcake particularly liked Sathya and went to live with her after the Stalker Fang was destroyed.
It is not known what happened to Sathya after the end of A Darkling Plain, but it is speculated she was freed from her official exile but may have stayed where she was; by the time Fishcake went to live with her, she was already an old woman so she may have died not long after the events of the last Mortal Engines book.