A native of the Western Caves, Nocturn and his fellow Echo fell afoul of a Dragon at Smokey Mountain, but were saved from harm by the timely intervention of Princess Luna. Out of gratitude, the pair swore themselves to her service as Royal Guards; though not the only ones in her service, they were designated to pull her chariot. On one occasion, the pair brought it to Ponyville so that Luna could attend Nightmare Night, though they left quickly after Luna leaped from the chariot to drop to the ground. Later, after Luna learned that the residents of Ponyville intended to honor her with a Winter Moon Festival-and intruding in their dreams to interfere with it-Nocturn and Echo once again pulled her chariot to travel there.
Despite this visit taking place during the day, the pair willingly accompanied their princess, donning reflective sunglasses to enable their eyes to endure the sunlight.On the day of the festival, Nocturn and Echo pulled Luna's chariot to Ponyville once again, and were present when the festivities were interrupted by the arrival of a Tarax Hippo. Once the beast had been subdued, Nocturn stepped forward and, after bowing his head to Luna, joined the other attendees in honoring her. Nothing certain is known of Nocturn's subsequent history.