Appearance and personality
Feryn does not have a description, but as a dwarf, he would have been in the 4 ft (1.2 m) range, and rather wider than a human, most likely with a beard.
As Zolf and Earhart explain in episode 61, Feryn grew up in Somerset and was "super keen" on being a miner like his father and grandfather. He joined the Harlequins after his father, Hirald, had stopped working for them as a logistical freelancer. Hirald didn't approve of Feryn's involvement with the Harlequins, but didn't stop him from working for them, and passed on his Harlequin ring to Feryn.
Feryn seems to have known, or at least be known by Amelia Earhart, through his affiliation to the Harlequins. After Feryn died, Zolf inherited his Harlequin ring; however, no one told Zolf what the ring meant. In episode 153, Zolf reveals to the party that he was accidentally responsible for Feryn's death. They had both been in a mining tunnel, and Zolf had been bored. He kicked at a wooden strut, which turned out not to be very stable. It collapsed, and resulted in a rockfall that killed Feryn. Zolf has blamed himself all his life.
In episodes 188 and 189, Zolf is confronted with an apparition with the voice and appearance of Feryn, which blames Zolf for killing him (Zolf agrees), and berates him for leaving him there. Through this interaction, despite this not being the real Feryn, we learn that Feryn's hand, from which Zolf took the ring, was the only part of Feryn that they could find under the rocks. We also learn that in Zolf's eyes, Feryn was the 'golden boy', i.e. their parents' favoured child.