Peter II was the grandson of Tsar Peter the Great
and his first wife Eudoxia. Peter II's mother, Princess Charlotte of Wolfenbuttle, died shortly after giving birth
to him, and his father Alexei had died, probably from the aftereffects of torture
during an interrogation
inflicted on him to confirm to the older Peter's satisfaction that Alexei had conspired against him.
Peter II came to the throne in 1727 at the age of 11, after being named heir of his step-grandmother (Peter the Great's second wife) Catherine I. Catherine had been persuaded by her husband's and her own longtime friend and advisor Alexander Menshikov to choose Peter to come after her instead of her own daughters, because Menshikov felt Peter would have more support. (Menshikov also got Catherine's permission to marry young Peter to his own daughter Maria.) This meant punishment for any official who had helped in the downfall of Alexei, but there were not enough people in that group to make a difference against those who approved of going back to the male line of succession.
Menshikov dominated the young Tsar at first and packed the high offices of government with his own supporters. However, when he fell ill, Peter and his close friends (including Catherine I's daughter Elizabeth) realized that everything continued to run even without Menshikov, and in September 1727 Menshikov was arrested, stripped of his titles, and exiled to the Ukraine and later Siberia. The family of Peter's friend Ivan Dolgoruky became the favored group. He was betrothed to Ivan's sister. Peter disliked his grandfather's city of St. Petersburg and moved the government back to Moscow. Then, however, he contracted smallpox and died at the age of 14 on January 30, 1730, which was to have been his wedding day. He had not named an heir, and was eventually succeeded by his cousin, Tsar Ivan V's daughter Anna.
Sources: Robert K. Massie's Peter the Great: His Life and World and those listed under Monarchs of Russia.