I cannae say why we have lost the second person pronouns, when both the Latin languages and the Germanic have kept them. I'm curious and will nose around.
Meanwhile, "thou" is the nominative, equivalent to "I". "Thee" is the objective, equivalent to "me". "Fare thee well" would be parsed: {May it} fare {to} thee well.
And as for the Ohrwurm, I'd rather have a bookworm.