Reasonable is etymologically related to Reason. Reasonable is the opposite of Remote. Remote is a synonym of Faint. 
Desperate is similar to Dangerous. Dangerous is related to Fire. Fire is related to Destruction. 
Reason <--EtymologicallyRelatedTo-- Reasonable <--Antonym--> Remote <--Synonym--> Faint 
Desperate <--SimilarTo--> Dangerous <--RelatedTo--> Fire <--RelatedTo--> Destruction 