Which entity is this text about?

Hasan ibn Ali ibn Muhammad (c. 846 - 874) was the 11th Imam of Twelver Shia Islam, after his father Ali al-Hadi. He was also called Abu Muhammad and Ibn al-Ridha. Because Samarra, the city where he lived, was a garrison town, he is generally known as al-Askari (Askar is the word for military in Arabic). Al-Askari married Narjis Khatun and was kept under house arrest or in prison for most of his life, until, according to some Shia sources, he was poisoned at the age of 28 on the orders of the Abbasid caliph Al-Mu'tamid and was buried in Samarra.

Various legends relate to al-Askari's wife, Narjis Khatun (the mother of the twelfth Imam, Muhammad al-Mahdi). It is said that al-Askari's father, Ali al-Hadi, wrote a letter in the script of Rum; put it in a red purse, with 220 Dinars; and gave it to his friend Bashar ibn Sulaiman. The letter instructed him to go to Baghdad, to a ferry place on the river where the boats from Syria were unloaded, and female slaves were sold. Bashar was told to look out for a shipowner named Amr ibn Yazid, who had a slave girl who would call out in the language of Rum: "Even if you have wealth and the glory of Solomon the son of David, I can never have affection for you, so take care lest you waste your money." And that if a buyer approached her, she would say "Cursed be the man who unveils my eyebrow!" Her owner would then protest, "But what recourse do I have I; I am compelled to sell you?" "You will then hear the slave answer", said the Imam, "Why this hast, let me choose my purchaser, that my heart may accept him in confidence and gratitude."  Bashar gave the letter, as he was instructed, to the slave girl; who read it, and was not able to keep from crying afterward. Then she said to Amr ibn Yezid, "Sell me to the writer of this letter, for if you refuse I will surely kill myself." "I therefore talked over the price with Amr until we agreed on the 220 Dinars my master had given me," said Bashar. On her way to Samarra, the slave girl would kiss the letter and rub it to her face and body; and when asked by Bashar why she did so despite not knowing the writer of the letter, she said, "May the offspring of the Prophet dispel your doubts!" Later on, however, she gave a full description of the dream she had had, and how she had escaped from her father's palace. A lengthier version of this story is recorded in Donaldson's book, along with further discussion on the authenticity of this story.  Some Shia sources have recorded her as being a "Roman (i.e. Byzantine) princess" who pretended to be a slave so that she might travel from her kingdom to Arabia. Mohammad Ali Amir-Moezzi, in the Encyclopedia of Iranica, suggests that the last version is "undoubtedly legendary and hagiographic".
Hasan al-Askari