Step is a type of Travel. Accompany is a type of Travel. Accompany is related to Date. 
Butterfly is related to Swim. Heat would make you want to Swim. Fire requires Heat. 
Step --IsA--> Travel <--IsA-- Accompany <--RelatedTo--> Date 
Butterfly <--RelatedTo--> Swim <--CausesDesire-- Heat <--HasPrerequisite-- Fire 