Biroc

Biroc was a Tharil who had been taken as a slave by humans. Rorvik took him to his ship and used him to navigate the time lines and help his crew and him escape from the Gateway.

When he failed, Sagan and Kilroy took Biroc to get medical attention, but Biroc knocked both of them out and escaped. He then breached the Doctor's TARDIS, where he briefly encountered the Fourth Doctor, Romana, Adric and K9 Mark II. He returned to the Gateway, where he and the Doctor travelled back to the day that the Tharils were overthrown by the humans.

Realising their past mistakes, Biroc helped the Doctor and Romana escape the slaver ship before its destruction. Romana and K9 then decided to stay in E-Space to assist Biroc in freeing his species from slavery. (TV: Warriors' Gate)