Sergei's three wishes reveal the selflessness and sincerity he holds within him for others. Every time he puts the needs and pain of other people before his own and tries to ease others. For example hi three wishes are:
1) To cure his sister of cancer
2) Heal Sveta's son without telling Sveta how it came about
3) Bring Yonaton back to life even though Sergei knows he will have to set the
fish free.
All of the above are wishes to ease other people's pain not his own.