F'duril was a dragonrider for Fort Weyr late in the Sixth Pass. His dragon was blue Dilenth.
When Dilenth was severely injured by threadfall, F'duril had to try very hard to comfort him because Dilenth's injury was one of the worst a dragon could sustain - both the leading and trailing edges of the mainsail were involved. F'duril blamed himself because he thought he should have held them between longer. Moreta finally had to tell F'duril to get a grip because he was upsetting Dilenth far more than the Threadscores on F'duril’s body.
When Moreta and A'dan examined Dilenth's injuries, they saw that if the dragon had emerged from between a second earlier, F'duril would have been knocked off Dilenth by Thread.