He is 'seeking revenge for' his father's murder. [=he wants to harm the person who killed his father]
He swore to 'take (his) revenge on' his enemies. [=to harm his enemies]
The bombing was 'in revenge for' the assassination of their leader.
(..) fertile in the Seven Kingdoms, - feeding horses and soldiers. - Yes, yes, yes. The Tyrells have not yet declared for any of the surviving kings. Loras wants revenge. He blames Stannis for Renly's death. And Margaery-- Wants to be queen. Yes, she does. House Tyrell rebelled (..)2012 TvShow: Game of Thrones Title: The Old Gods and the New Season: 2 Episode 6