Eliza Cooper was an agent of the Torchwood Institute.

In 1889, she and Robert Lewis traced the Tenth Doctor and deduced that he was stranded in London. (COMIC: The Time Machination)

In 1906, Eliza and Robert went through a time machine. They were transported to a different planet thousands of years in the future. There they encountered the Doctor. They tried to arrest him. Eliza however, soon realised that they needed the Doctor to return home. She was ready to trust him, having seen his heroics in their files and heard Jack Harkness speak about him.

Eliza decided to stay on the planet and help its inhabitants rebuild their world. (COMIC: Final Sacrifice)