Merla is a winged horse, born in the Twelfth of the Ram in Remora shortly before the Stellata. Her mother is Starlight, a favourite mare of Cesare Montalbano, the son of Paolo, the Horsemaster of the Ram.
While the birth of a winged horse is not impossible, it is incredibly rare and seen as a sign of good luck for the Twelfth of the Ram, which has not won a Stellata in more than twenty-years. Paolo names the filly "Merla," meaning blackbird, because she is completely black. As a winged horse, she grows much more rapidly than an ordinary horse. Unsurprisingly, she is fully capable of flight once she is sufficiently grown.
Despite the Ram's attempts to keep Merla a secret, she is abducted by Enrico Poggi for the di Chimici and kept in the neighbouring town of Santa Fina. On the day of the Stellata, she is found by Luciano, who went to Santa Fina in hopes of finding Cesare, who had also been kidnapped by Enrico. Cesare returns to Remora riding Merla and arrives just as Georgia O'Grady wins the Stellata for the Ram. Merla becomes famous as the Sorte di Montone, the luck of the Ram.
At the conclusion of City of Stars, Georgia keeps one of Merla's feathers, which she gives to Falco as a new talisman to return to Talia. During their return to Remora, Falco rides Merla during the special Stellata held in his honour, repeating Cesare's feat from the previous Stellata.
Merla subsequently appears in City of Flowers, where she transports Georgia to Giglia from Remora during Georgia's stravagations to Talia. In Giglia, she is cared for by Raffaella and Aurelio Vivoide, two of the Manoush. Because of her tremendous popularity following the Stellata of 1578, she and her mother are eventually moved to the Ram's auxiliary stables in Santa Fina.