Tia is a friend of Cloak form before he became a superhero. At that time she was his girlfriend. When he returned she had found out has secret and a team of solder-like people who wanted to force him to forget his powers. It was revealed that she had power and had forgotten them, but Dagger made her remember. She ran away and had her powers forgotten.
 

Powers

The full extent of her powers is unknown but she had some form of teleportation or super-speed. Her power most likely came from the same drug that gave Cloak and Dagger their powers.