Hector was a Pleasure GELF, created to be everyone's perfect companion. Hector was also a brilliant scientist and spent many years trying to overcome his genetic programming and live an independent life.
Although they were an androgenous species (having no gender), he fell in love with another GELF called Camille. They worked together until she left him and ventured off into space. Hector began searching for her, as she was his great inspiration and part of his work.
When Camille was rescued by Kryten and taken to Red Dwarf, Hector followed her and demanded to be allowed aboard. Kryten lied to Camille, telling her that she needed to be with Hector because he could love her in a way that Kryten never could and that she had to help Hector finish his research. She agreed and the two GELFs left together.
Hector only says one line in the episode - "Are you ready Camille?" He has a German accent.