Gold Petals is a young mare from Windthrow. She is introduced as a stallion named Gold Plate. (Due to a mistake, the author calls "him" "Sun Plate" for the first couple of chapters, and "Iron Plate" a few times.) She pretends to be a stallion in order to escape the domestic life expected of mares in Windthrow, and to join Fulltrot's trade caravan. Fulltrot actually knows her secret, but hasn't said anything to her; the other stallions in the caravan don't notice. She is in charge of the caravan's food supplies, and is treated somewhat as a punching bag, mocked for her youth and lithe physique.
Gold Petals has a short golden mane, an amber coat and blue eyes; except for the eyes, she apparently reminds Rainbow Dash of Applejack. She wears a brown hood to hide her feminine features, and leather armor like other members of the caravan.
Noticing her is the reason Rainbow Dash decides to join the caravan instead of flying onwards; Dash apparently immediately sees through her disguise as well. In the forest night at Windthrow, Rainbow confronts her with her knowledge of the truth, and then they are immediately attacked by chaos monsters. Some time later, she stays by Dash's bedside when Rainbow has a dizzy spell.
When Rainbow is back from rescuing Rockspot and Ironhoof accidentally activates Sladesteed's chaos strip, Rainbow flies with her to the machine world to safely contain the two chaos strips and the monsters following them (Rainbow can't hold the chaos strips herself, as they trigger her dizzy spells). After an epic chase, complete with barrel rolls, they manage to seal the monsters and thus free Windthrow from them.
Gold Petals didn't get along well with her parents, and was thus rather lonely in Windthrow. However, she makes up with her parents after her heroic defence of Windthrow, and also stops hiding her gender, presumably being accepted by her village.
Romantic tension between her and Rainbow Dash starts building already on the way to Windthrow, and culminates with a kiss at the end of the Windthrow arc, after which Rainbow immediately escapes, heading east, due to a painful memory of Applejack.