Marsh has brown scales and brown eyes. He looks like Sora, just more fidgety and nervous.
Marsh is an extremely nervous and jumpy character, and is described by Umber to be able to fly extremely fast. Like most MudWings, he cares a great deal about his sibs and is afraid of seeing another one of them die like Crane. He seems to get along well with Coconut, his clawmate and another member of the Copper Winglet, possibly because of his placid personality. Like his other sibs, he did not enjoy the war and often wished for it to end.
He never seemed to have recovered from the death of his sister Crane, who was killed by Icicle in a battle between Blaze and Burn's armies during the War of SandWing Succession. As it was his troop's first battle, the aftermath of the events left even more him scarred and possibly traumatized.
After they escaped from the Sky Kingdom, Clay and the other dragonets of destiny made their way to the Mud Kingdom while being pursued by Burn and her soldiers. The group encountered him and was overjoyed to see him for the first time, helping him make peace with himself. Despite protests, they let Clay depart to be the bigwings of the prophecy dragonets, leaving Reed to remain as the troop's bigwings, if with doubts about his own leadership on the fact that Clay was they're natural bigwings.
Marsh was mentioned in the prologue of the fourth book with his siblings when IceWings attacked the patrol's SandWings nearby. He was terrified and tackled Reed midair, nearly taking Reed down with him.
Marsh appeared in Clay's dream with his other siblings when Starflightdreamvisited Clay.
Marsh and his siblings were seen when Sunny and Clay go to the MudWings in order to send a message to Burn. He admitted to feeling wary of the outcome of the MudWings' planned attack on the IceWings, which, thanks to the Great Ice Cliff, would have ended in suicide, though they did not appear to know it was there.
Marsh accompanied Clay and his siblings throughout the book and attending Jade Mountain Academy as part of the Copper Winglet. Near the end of the book, when Sora was asked why she tried to kill Icicle, Marsh was shown in a flashback. Sora and Marsh are about to be killed by an IceWing and Crane save them by pushing them out of the way.
When Umber abruptly left with Sora, they didn't have time to tell Marsh that they were leaving, leaving Clay with the responsibility of breaking the news to his younger brother.