Agda Persdotter is believed to have been the daughter of the wealthy merchant Peder Klementsson, who lived by St Nicolai port in Stockholm and was known as Pher i Porten, though her parentage has not been confirmed. She was described as a great beauty, and was called Charitas. She became the mistress of Eric during his time as a crown prince, and is the first of his recorded mistresses. She was a center of his court at Kalmar Castle in 1558, where a chamber, Agdas kammare, (= "The Agda Chamber") is still named after her. Their relationship continued after he became king in 1560.
In 1561, she was married to the noble Joakim Fleming and given the estate Eknaholm outside Växjö, which had belonged to a monastery. The relationship with Eric ended, and resumed only after she became a widow in 1563. The relationship was not exclusive, as Eric had a large number of other mistresses; during the period 1561-65, Anna Larsdotter, Karin Jacobsdotter, Karin Pedersdotter, Sigrid Nilsdotter, Doredi Valentinsdotter and the more anonymous Britta and Ingrid were all listed as the King's mistresses, but Agda was his main mistress. The position of these women was only semi-official.
She had several daughters with Eric, and one daughter with Joakim, Anna (born 1562). In 1561, the custody of her children was given to the king's sister, Princess Cecilia of Sweden, because, as Eric said: "I know she is not capable of raising them in good discipline and other things". When Cecilia left the country in 1564, their care, and that of the other children of Eric, was entrusted to Princess Elizabeth of Sweden. One of Elizabeth's servants, Karin Månsdotter, took care of Virginia. In 1565, Karin became the one and only mistress of Eric and replaced Agda and all the others. Agda remarried the noble Christoffer Olsson Stråle av Sjöared, sheriff of Stegeborg.
- Hans Gillingstam, "Agda Persdotter, hennes släkt och Erik XIV:s dotter Lucretia. En källkritisk studie", Släkt och Hävd 2001:2-3, s. 156-160.
- Herman Lindqvist, "Historien om Sverige: Gustav Vasa och hans söner och döttrar."
- Lars-Olof Larsson, "Arvet efter Gustav Vasa"