Paul I of Russia
Paul I (; "Pavel Petrovich") ( – ) reigned as Emperor of Russia between 1796 and 1801. Officially, he was the only son of Peter III and Catherine the Great, though Catherine hinted that he was fathered by her lover Sergei Saltykov, who also had Romanov blood, being a descendant of the first Romanov tsar's sister, Tatiana Feodorovna Romanova.
Elizabeth of Russia
The young Peter had lost his mother, Elizabeth's sister Anna, at three months old and his father at the age of eleven. Elizabeth invited her young nephew to Saint Petersburg, where he was received into the Orthodox Church and proclaimed heir on 7 November 1742. Elizabeth gave him at once Russian tutors. Keen to see the dynasty secured Elizabeth settled on Princess Sophie of Anhalt-Zerbst as a bride for her nephew. Incidentally, Sophie's mother, Joanna Elisabeth of Holstein-Gottorp, was a sister of Elizabeth's own fiancé who had died before the wedding. On her conversion to the Russian Orthodox Church Sophie was given the name Catherine in memory of Elizabeth's mother. The marriage took place on 21 August 1745. Nine years later, a son, the future Paul I, was finally born on 20 September 1754.