Mia Cooper was a powerful healer who was friends with Dax Jones, Gideon Reader and Lisa Hardman. She had a gentle and compassionate nature, and was a vegaterian. Because of her powers, when people first meet her, they became entranced with her, in what Gideon calls "The Mia Effect". She was embarrassed about the Mia Effect, and was grateful when her friends made fun of it.

In the fourth book (Dowsing the Dead), she got a black obsidian bracelet, which made her more aggressive, and she also became a pyrokinetic. She also made bracelets for the rest of the COLAs.

She could heal people with a touch, but at the end of the first book, Owen Hind reveals that she knew of no way to release the pain she absorbed from others. This caused her to gradually weaken. For example, Mia healed Spook Williams' broken ankle, and Dax saw her limping away, but didn't realise why. Later, he noticed that she looked tired and sickly, and learnt that she collapsed while trying to heal Caroline Fisher's injuries.

She lived with her father on a poor council estate, and in the third book, it revealed that her father drunk a lot, and she had been healing him.

She was pale, with brown hair in a short bob, and violet blue eyes.

She played a major role in Stirring the Storm, where she burnt the lead antagonist, Catherine Reader, to death with her pyrokinetic abilities.