What is XXX's brothers name?
Marfa Alekseyevna of Russia
Tsarevna Marfa Alekseyevna of Russia (Russian: Марфа Алексеевна; 26 August 1652 -- 19 June 1707) was a Russian princess, daughter of Tsar Alexis of Russia and Maria Miloslavskaya, sister of Tsar Feodor III of Russia and Tsar Ivan V of Russia and half-sister of Tsar Peter the Great.
Feodor III of Russia Ivan V of Russia Peter the Great