Adin, on his way to Jaliad, came across Greel's hut, intending to use the seemingly abandoned place for shelter. Greel burst out and challenged Adin, ignoring Adin's attempts to explain himself. The two clashed swords, and Greel overcame Adin with relative ease. However, Greel was impressed with Adin's skill and, as thanks for the good fight, allowed Adin to live and feast with the Jalis for a night. Greel took Adin to Jaliad and, on the way, told a confused Adin about his clan. In particular, Greel mentioned an ancestor that killed a goblin in his hut, showing Adin the goblin's talisman.
Upon reaching Jaliad, Greel offered Adin a feast and allowed him to tell his tale; if his tale was entertaining, they would release Adin and chase him, but if not then they would kill him on the spot. Though the Jalis initially heckled him, they fell silent when he described himself as a man that worked "with iron and fire". Adin explained his dream and the belt that he was creating, offering the Jalis the chance to be the first to offer their gem to the cause.
Instead of killing him, as Adin had expected, Greel spoke very seriously, asking if the blacksmith had ever heard of Tenna of the Jalis. When Adin said that he had not, Greel explained the Tenna Birdsong Tales. He then humbly requested that Tatti, Tenna's descendant and the Jalis' current storyteller, to tell Adin a particular tale: the tale of Opal the Dreamer. When the tale was finished, Greel himself retrieved the Diamond and personally fixed it to Adin’s belt. Before Adin left Jaliad, Greel taught him swordplay so that he would be more able to defend himself on his journey.
Greel participated in the Battle for Deltora, fighting at Adin's side at one point. When the Belt of Deltora was completed and the Shadow Army was driven away, Greel and the rest of the Jalis expressed their joy by bellowing and slaying green beasts. They later joined the other tribes in Hira for a celebratory feast.
Greel, like all Jalis, wore a suit of ornate, golden armour. Greel's armour was adorned with spikes and patterns resembling vines. His helmet sported three curved horns — one on the back of his head and two in the front — and a T-shaped visor. He was an enormous man with an equally enormous and heavy sword. The hilt of Greel's sword was decorated by a carved dragon's head, with the dragon's mouth wrapped around the base of the blade. Greel wore what he believed to be a goblin's talisman around his neck, though in reality he held the mouthpiece of the Pirran Pipe. His face was described as "brutish" and he had bushy eyebrows.
Like most Jalis, Greel fought first and asked questions later. When Adin first met Greel, the knight expressed hatred towards the Del tribe and demeaned them as being "worms". After defeating Adin, however, it was shown that his love of a good fight was greater than his hatred of "weaklings", and he allowed Adin to live for a while in honour of his effort.
Despite his gruff exterior, Greel, like most Jalis, sincerely believed in the Tenna Birdsong Tales, and this was the main driving force behind his decision to give Adin the diamond, which he did without hesitation. Though he was the leader of his tribe, Greel was very good-natured toward other Jalis and highly respectful toward Tatti. He was rather superstitious, perhaps even more than most Jalis, and believed that his clan's talisman had magical powers that protected him from harm.
Greel was very physically powerful, able to wield his heavy sword with ease. He had immense stamina and was highly skilled in swordplay, which made him a formidable warrior. Greel believed - incorrectly - that his talisman made him invulnerable in combat.