Isadora was born in 1913 in Selvadorada to Violeta Fiorellá, a popular village baker, and Phillip de Costa, heir to the Shallot Throne. She had a half brother through her father, Sebastián de Costa. Her early childhood was neglectful, as her mother was either constantly working in the bakery, or visiting with Phillip. 

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At only age 5, she lost her mother, father, half-brother, and her father’s wife, Penelope when they perished on a shipwreck off the coast of Selvadorada in 1918, thus resulting in her becoming an orphan. She only survived because her mother left her behind with her elderly mother, Camelina to visit with Phillip on board. Reign Escargot-Shallot, brought Isadora to Windenburg after her parent’s death to live as his adopted daughter at the estate. Reign raised Isadora alongside his own children, Lord Bernard II, and Lady Elaine II. She grew close to them, though she always knew she was not the same. They were of full royal blood, while she was born out of wedlock to a mistress. But Reign always wanted to make sure she was comfortable. While the press had a frenzy when Isadora was set to marry Lord Bernard II, The Shallots were quite happy, as they all loved Isadora dearly. 

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They married in 1930 when Isadora was 17. Their marriage was happy and produced three children, Lord Bernard lll, Lord Reign ll, and Lady Camilla. 

She ruled Windenburg with her husband until his death in 1957, when she then stepped down and allowed her eldest son to rule. She passed away in 1965 at age 52 due to illness.