Fallow was placed in Del by the Shadow Lord after the death of Prandine. Fallow served as the leader of the Shadow Lord's forces in Del for roughly sixteen years, though he usually made the Grey Guards perform his daily duties. At some point before the Emerald was recovered, Fallow had Lief's parents imprisoned.
Lief, using the water from the Dreaming Spring, watched as Fallow interrogated Endon – though Fallow believed that he was speaking to Jarred. Endon mistook him for Prandine, though Fallow quickly corrected him, explaining that the Shadow Lord simply preferred that he take Prandine's form. Fallow interrogated "Jarred" about his involvement in Prandine's death, the disappearance of King Endon and Queen Sharn, and the recent theft of the gems from the Belt of Deltora.
Endon feigned ignorance, and when Fallow asked where Lief had gone, Endon lied and said that his son had run away. Fallow revealed that he knew that a boy of Lief's age, a girl accompanied by a black bird, and a grown man were responsible for stealing the gems. Fallow left Endon, having learned nothing, but threatened to torture "Anna if he did not give him more information next time.
Lief managed to deduce that Fallow was a Grade 3 Ol, based on Fallow’s comments when he was speaking to Endon, and later spied on Fallow directly using the Dreaming Water. Lief watched as Fallow basked in a peculiar green light before the Shadow Lord summoned him. Fallow spoke to the Shadow Lord through the crystal. He explained that "Jarred" had still not revealed any new information, despite numerous threats and starvation. Fallow confessed that he was beginning to think that Endon truly knew nothing.
However, the Shadow Lord berated Fallow for his failure, insisting that the blacksmith was lying; he revealed that he knew for a fact that Lief and Barda were responsible for retrieving the gems, having been informed by a spy. Fallow, enraged, planned to kill Lief's parents, but the Shadow Lord angrily ordered him not to, so that they could be used against Lief as hostages.
Fallow was mentioned by the Grey Guards preparing to execute Dain. They were waiting for him to begin the ceremony, but Fallow would not answer his door. Later, Fallow himself appeared at the Place of Punishment, preparing to execute Glock, Zeean, Manus, Fardeep, Nanion, and Gla-Thon. Fallow failed to notice Lief climbing above the Place of Punishment, his attention drawn by the Ak-Baba, the Shadow Lord, and his prisoners. When Jasmine was brought to Fallow, Lief leapt onto the platform to give her the Belt, but Fallow seized him. However, Lief's parents surprised Fallow, wrapping their chains around his neck and forcing him to release Lief. Fallow stabbed Endon, mortally wounding him, before all three of them fell from the platform.
Fallow freed himself from their hold, but he grasped at one of the cones that provided light for the platform, tipping it towards himself. He was doused in the searing hot, glowing liquid in the cone, and screamed in agony before dying.
Fallow was given significantly more screen time in the Anime. He appeared in nearly every episode, usually before the crystal to inform the Shadow Lord of the companions' progress. He was also tied to several key points in the anime that his book counterpart never dealt with. Notable examples are sending the sorcerer Oacus after the companions and distracting Dain long enough for Lief to kill him with the Belt. His addiction to Lumin was left out of the anime. The only scene from the books that remains the same is Fallow's interrogation of Endon.
Fallow lead the Shadow Lord's forces against the Resistance in the final battle for Deltora. He fought with Barda briefly, who confused him for Prandine, and was defeated. He then attacked Lief and was defeated again, but escaped onto the back of one of the Ak-Baba. Lief followed after him, and the two fought in the air, Fallow growing wings through his shapeshifting abilities. During the battle he grabbed hold of the Belt of Deltora. It destroyed him, but the gems are separated from the belt again.
Fallow's appearance was identical to that of Prandine; he was a tall, thin man resembling a bird of prey. He wore long robes and had bony fingers. He had a sour expression and had a scary figure. Fallow was also capable of taking any form he wished, but the Shadow Lord preferred that he retained Prandine's body.
Fallow was more openly malicious than Prandine, as the Shadow Lord no longer needed a subtle manipulator. Conversely, he seemed less competent and focused than his predecessor. Fallow was a cruel individual, willing to torture and imprison the friends and family of those he suspected were plotting against the Shadow Lord. He was addicted to Lumin, a strange, sickly green light that the Shadow Lord provided him with, but it dulled his mind and made him forsake his duties frequently.
In the anime, Fallow appeared to fear the sorceress Thaegan, as he often cowered from her every time she was revived. He did not act this way towards Oacus however, most likely because Oacus was a fellow servant of the Shadow Lord while Thaegan was an ally.
Fallow, as a Grade 3 Ol, was capable of shapeshifting into any form he desired and retaining that form for as long as he wanted. Though mildly intelligent and observant, Fallow was not clever enough to see through Endon's lies. It is implied that Fallow's addiction to Lumin damaged his brain, dulling his thinking ability. Fallow was given command of the Shadow Lord's forces in Del – and, to a lesser degree, all of Deltora – and received orders directly from the Shadow Lord. Fallow also owned a dagger for protection.