Mila was a Cardassian woman, the housekeeper of former Obsidian Order head Enabran Tain for over thirty years. Mila was Tain's closest confidante, since even though she "wasn't much of a cook", she knew how to keep secrets. Mila was fond of Tain's son, Elim Garak, whom she practically raised as her own child. Mila always firmly believed that Garak was innocent of Tain's allegations of betrayal.
In 2371, Garak contacted Mila for the first time since his exile, concerning Tain's whereabouts after the deaths of several former Obsidian Order agents. Mila informed him that Tain had departed in a hurry, and pleaded Garak to help him. (DS9: "Improbable Cause")
When Garak and Tain reunited, Tain idly considered executing Mila as she knew "too much for her own good." Garak objected, rationalizing that she was both trustworthy and a capable housekeeper. In truth, he was as fond of her as she was of him. (DS9: "The Die is Cast")
After Garak, Damar, and Kira Nerys were stranded on Cardassia Prime in 2375 when the Cardassian Liberation Front was wiped out by the Dominion, Mila sheltered them in the basement of Tain's house, from which they organized a new civilian resistance movement. Unfortunately, their whereabouts were discovered, and Mila was killed by Jem'Hadar troops just before the end of the Dominion War. (DS9: "The Dogs of War", "What You Leave Behind")
The Star Trek: Deep Space Nine novel A Stitch in Time reveals that Garak was raised believing his parents were Mila and Tolan. Shortly before his own death, Tolan told Garak the truth about his parentage. After Tolan had died, Mila explained to Garak that Tolan was her brother.