An allusion, such as “a Scrooge” is a reference to a well-known person, place, thing, event, or literary character. If you refer to someone as a Scrooge, you are implying that he is . at the place where a person meets failure, from Napoleon’s battle at Waterloo

a romantic boy or man, from Shakespeare’s Romeo and Juliet

a stingy person, from Charles Dickens’ A Christmas Carol