- "I have a plan. If this proves to be an ambush, Aram will kill everyone. And their horses."
- — Ferrin
Ferrin is the son of Baldor, but nothing else is known about his family or childhood. Like all displacers, he was trained from a very young age to lie, betray, spy and conduct espionage for the emperor.
At some point in his life, Ferrin met and fell in love with a woman of Trensicourt who did not realize he was a displacer; however, she was already engaged, and when her fiancé found out, he challenged Ferrin to a duel. Ferrin ended up killing the man out of self-preservation. The man was a cousin of Chancellor Copernum, and Copernum took revenge by publically beheading Ferrin. However, as he was a displacer, he was not actually killed by this, and a few friends helped him get away. His girlfriend found out he was a displacer, and that was the end of their relationship.
Sometime later, Ferrin was apparently sent by Maldor to spy on Jason and Rachel as they searched for the Word. While at first he pretended to help them, his true allegiance was eventually found out, and he left the pair, claiming that he had really grown close to them and regretted having to betray them to his master.
Later on, Ferrin freed Jason from imprisonment in Felrook, knowingly committing an irrevocable crime against his master and becoming almost as wanted as Jason himself. Ferrin then tried to befriend Jason, ending up assisting in the rebellion against Maldor. While hoping that Ferrin was truly on their side, as an extra precaution against betrayal, Galloran asked Ferrin to remove part of his carotid artery and give it to him so that if he ever betrayed them, they could poison him; if he were to release the connection, he would bleed to death.
Ferrin helped teach Jason swordsmanship and discovered the grafted ear on Nedwin. But after experiencing true friendship from Jason (a rare feeling for displacers), he willingly gave Jason a piece of another major artery in his arm (brachial artery) as an extra assurance. While many times being tempted to turn in the rebellion to Maldor and thus stay loyal to his race, Ferrin continued to help Jason and his friends in their conspiracy against Maldor.
When Tark volunteered to give his life blowing up the ancient orantium mine under Felrook, Ferrin was desperately close to betrayal. He made his way into the cave and told Tark how he felt, but then decided to stay and help Tark open up the passage to the orantium. He and Tark both died in the subsequent explosion.
Ferrin appears as an echo, or ghost, in Death Weavers, the fourth book in Brandon Mull's Five Kingdoms series.