Serious is a synonym of Grave. Grave is related to Stone. Stone is related to Color. 
People can be Thin. Dying can be used for People. Dying is similar to Eager. 
Serious <--Synonym--> Grave <--RelatedTo--> Stone <--RelatedTo--> Color 
Thin <--HasProperty-- People <--UsedFor-- Dying <--SimilarTo--> Eager 