At the beginning of Lunar: The Silver Star Story, Nall is the constant companion of the protagonist, Alex, having been delivered to Alex's family at the same time as Luna. Nall appears to be a small, white cat with wings enabling him to fly. While he looks like a feline and has a number of catlike habits, including a predilection for fish, he is a sapient being and dislikes being called a cat. He is chatty and sarcastic, and his big mouth sometimes gets him into trouble. It is later revealed the Nall is an infant White Dragon, heir to the powers of White Dragon Quark, one of the Four Dragons who protect the goddess Althena. After Quark's death at the hands of the Magic Emperor, Nall accepts his powers and uses them to help the party. While he can take on a larger, more traditional draconic form, he spends the vast majority of the game in his smaller form.
In Lunar 2: Eternal Blue, Nall has taken over the remains of the Grindery, now known as Taben's Peak, and converted it into a hideout and foster home for orphans. Having learned to take a human form, that of a teenage boy with classical punk hair the color of Nall's fur, he flies about in dragon form looking for abandoned children and, as human, offers them a place to stay, with the condition that the child leaves to make his or her own way when he or she grows taller than Nall's human form. Few if any of the children, known as the Danger Kids, suspect that the "big white bird" which they occasionally see around the mountain and Nall are the same being, nor that he is the mighty White Dragon, and while some notice that Nall occasionally seems unbearably sad, they can't imagine the cause: the lingering pain of losing his very best friends to old age 1000 years previously.
Nall's orphanage is a sort of Neverland, with few rules or restrictions, other than that the children must depart when they exceed Nall's height. While the children tend to drive outsiders away with pranks and traps, they're more mischievous than malicious and are very happy in their carefree world. Some fans argue that such an environment, without a real social structure or the influence of genuine parents, would ultimately be psychologically unhealthy for children, but a few of the game's NPCs speak fondly of their days as Danger Kids and seem to have integrated well into society.
When Nall first encounters Hiro and the party, he immediately recognizes Ruby for what she is, though he does not immediately reveal his identity. As he aids the party with his 1000 years of knowledge (his magical powers having been sealed by Zophar's agent Ghaleon), he attempts to convince Ruby that she is too deeply attached to Hiro, and that she should give up her ambitions of a romance between herself and Hiro, as his inevitable death would cause her similar emotional pain. He tells her that eventually only the memories of her time with Hiro and their other friends will remain, and that she should prepare herself for that while cherishing the time she has. As a human, Nall carries Althena's Sword (once wielded by his friend Alex) tied with Luna's scarf, as memoirs of his long-dead friends. Seeing Hiro's need for it, however, he gives Althena's sword to him.
Romantic interest between Nall and Ruby is suggested but not explicitly displayed.