Yassen Gregorovich
Alex first met the Russian contract killer who killed his uncle on Herod Sayle's ground during his mission in Stormbreaker. At the time, Alex originally vows to kill him. Later, during the events of Eagle Strike, it is revealed that Gregorovich worked with Alex's father John 15 years prior. When Gregorovich's friend captures Alex, Gregorovich is able to arrange for Alex to do bullfighting instead of being shot directly, leading to Alex being able to escape. At the end of the novel, when Damian Cray (the man who hired Gregorovich) orders him to kill Alex, he refuses and is shot and killed. Before dying, Gregorovich tells Alex that he worked with his father and to go to Venice and find Scorpia to find his destiny.
Read more about this topic: Alex Rider (character), Relationships