Vladimir Putin
Chris Hutchins, a biographer of Russian Prime Minister Vladimir Putin, describes the relationship between Russian president and Abramovich as like that between a father and a favorite son; Abramovich himself has stated that his relationship with Putin is a professional business relationship, as signified by his use of the Russian language's formal "Вы" (like Spanish "usted" or French "vous") in addressing Putin, as opposed to the informal "ты" (Spanish "tú" or French "tu").
Read more about this topic: Roman Abramovich, Relationship With Kremlin