Io is notable as having been the homeworld of the Arnold Rimmer and the Rimmer family, who had originally hailed from England on Earth, and whose lineage also included French and Austrian aristocracy, among others. (The Beginning)
A dull, rocky, volcanic world, Io was colonized by the Space Corps, whose humans had built domed colonies in order to shield its inhabitants from solar radiation, and create a suitable atmosphere and artificial gravity for living. Entire cities and botanical gardens were located within these domes. Io was a primary center of higher learning throughout the Solar System, and was also a primary hub of the Jupiter Mining Corporation.
Red Dwarf second technician Arnold Rimmer was born on Io in 2149. He spent his formative years on the moon before joining the JMC. The young Arnold was bullied mercilessly by his brothers, John, Frank and Howard. At one point, a young Arnold was left hanging upside down from a tree by his brothers. This was because they wanted to make a swing out of him. (Infinity Welcomes Careful Drivers, Dimension Jump). On another occasion, they put a landmine in his sandpit, and buried him up to the neck, covering him in jam and threatened to pour ants on his head. When they played "The Three Musketeers", they would only let Arnold be the Queen of Spain. (Polymorph)
Rimmer's boarding school, Io House, was on the moon. During his time there, he would sleep with over-starched pajamas and nocturnal boxing gloves. Arnold was bullied mercilessly by the gym teacher Bull Heinman, who thought he was too wet. Among his classmates was Thickie Holden, who went on to invent the Tension Sheet and become a multi-billionaire. (Timeslides)
As a boy, Rimmer was in the Space Scouts, and was once nearly eaten by his best friend Porky Roebuck on a survival course in the Ionian wilderness. It was only the timely intervention of the space mistress Yakka Takka Tulla that saved Rimmer's life. The event destroyed Rimmer's faith in friendship. (Queeg)
The only thing that Arnold's social father ever gave him was a camphor wood chest, a Rimmer family heirloom containing antique, Napoleonic toy soldiers. (Marooned) Arnold was obsessed with all things military from a young age, perhaps inspired by his family history, and the contents of the wooden chest. A young Arnold was an enthusiastic member of the Io Amateur Wargamers. Arnold's fantasies of military command would come to fruition three million years later, albeit with disastrous results, on Waxworld. (Meltdown)
Arnold had a failed teenage relationship with an Ionian girl named Fiona Barrington, with Arnold only actually getting "lucky" with a pile of warm compost instead, which he thought was Fiona. (The Inquisitor) Fiona was eventually stolen by Arnold's older and much more successful brother John. (Better Than Life)
When Kryten needed to knock a hard-light hologram Rimmer unconscious, he tried the "Ionian nerve grip". However, there was no such thing, and Kryten had made it up. Rimmer noted that the Ionian nerve grip was simply Kryten hitting Rimmer over the head with a vase. (Legion)
- Only a wider shot of the whole colony, and the gardens of the Rimmer family home, are seen in the episode "Dimension Jump", but not the Rimmer family home itself.
However, extended model work done for "Dimension Jump" can be seen on the Series IV DVD and includes models which were trimmed for broadcast. This includes the previously-unseen Rimmer family home itself; which was seemingly very modular, and resembling grain silos.