Eddie and Steve do not like each other. But they make an effort for the sake of Dustin.
When they realize that they don't really hate each other, Eddie confides in Steve and their bond strengthens.
Eddie Munson, 'the freak' of Hawkins high hated Steve 'the hair' Harrington, he was a douche and so clearly in love with himself, but did Eddie really hate Steve or did he hate the thought of seeing him with other girls?