Ri-Nan seemed to be the only Dread Gnome who was compliant with the wishes of the Ooze Toad Gellick. He believed that the Gnomes had been given a powerful gift in the form of Gellick's venom, and tried at every moment to get into the toad's favour. When Lief, Barda, Jasmine, and Prin were cornered in the Breeding Cave, he was the first Gnome to speak his scepticism when they claimed to be able to kill Gellick. He was overruled, however, when Jasmine—who had been struck by a poisoned arrow—was revived by the Ruby.
He accompanied the companions into the treasure room with Gla-Thon and Fa-Glin—mostly to make sure they did not run off with any treasure. However, he purposely woke the toad up to show him the traitors. He declared that he should be made leader of the Dread Gnomes, and that he could make them work twice as efficiently. Gellick, however, saw this as insolent and killed Ri-Nan with his venom.
The anime version of Ri-Nan stays mostly true to the book. However, Prin saved him from Gellick's venom. This act of kindness caused Ri-Nan to show remorse for his actions, and apologise to everyone. During the finale, he led an army of Dread Gnomes and Kin in the final battle against the Shadow Lord.
Ri-Nan cared only for himself and obtaining power. To this end, he became the only willing servant of Gellick, and always boasted about how the Dread Gnome's alliance with the toad was for the betterment of their entire tribe. Even when presented with a chance to regain his tribe's freedom, Ri-Nan betrayed Lief and the others to try and obtain favours from Gellick. This self-serving arrogance is what eventually lead to his death.
In the anime, Ri-Nan's life was spared by Prin who saved him from getting doused by Gellick's poison. This act of compassion from a being who had full justification to let him die and the realisation that he was nothing more than a slave to Gellick helped Ri-Nan finally realise his loyalties were misplaced and that he and the other Gnomes were wrong to hunt the Kin in the past. He ordered the other Gnomes to not attack the Kin when they returned to the mountain, and swore loyalty to Lief, Barda, and Jasmine, that the Gnomes would never again use the Toad's Poison for anything but to fight against the Shadow Lord's minions when came the final battle.