Ianto Jones is reserved and efficient. He is humorous asides to the episodes' scripts. The character is notable for being the main romantic interest of Captain Jack Harkness, who is the lead male of the series. Established to have had heterosexual relationships prior to the series, Ianto's story forms a part of the show's ongoing exploration of human sexuality. Expanded Universe material develops on Ianto's sexual orientation and the nature of the relationship with Jack, describing Ianto as bisexual and his feelings for Jack as genuine love. Additionally, writers have used these other media to explore Ianto's characterisation; for example, some stories elaborate on Ianto's backstory, or provide insight into his feelings.