Supporter is the opposite of Opponent. Opponent is related to Competition. Competition is a synonym of Rival. 
Spy is a type of Worker. Observer is a type of Worker. Observer is a type of Person. you are likely to find Liver in/at/on Person. 
Supporter <--Antonym--> Opponent <--RelatedTo--> Competition <--Synonym--> Rival 
Spy --IsA--> Worker <--IsA-- Observer --IsA--> Person <--AtLocation-- Liver 