Conversation so far:
What was the Rise to prominence for Grigori Rasputin?
Word of Grigori Rasputin's activity and charisma began to spread in Siberia during the early 1900s. Sometime between 1902 and 1904, he travelled to the city of Kazan.
What did he do in Kazan?
Grigori Rasputin travelled to the city of Kazan on the Volga river, where he acquired a reputation as a wise and perceptive starets, or holy man.
How did others perceive Grigori Rasputin?
Despite rumors that Grigori Rasputin was having sex with some of his female followers, he won over the father superior of the Seven Lakes Monastery outside Kazan.
Why were there rumors about Grigori Rasputin?
What are some other interesting aspects about the Grigori Rasputin article besides the rumors about him?
Upon meeting Sergei at the Nevsky Monastery, Grigori Rasputin was introduced to a number of different church leaders, including Archimandrite Feofan.

Question: Who was Sergei?
Self-contained rewrite: Who was Sergei in relation to Grigori Rasputin?