Fear means simply: “to be afraid of rebelling against the King.” That is a quote from the beginning of Tanya chapter 41. This definition includes the most primitive fear (fear of punishment, yiras onesh) and the most advanced fear (fear with bashfulness, y’rei boshes).

Fear in chassidus is a result of love inasmuch as one is afraid to lose what one has, i.e., we don’t want to lose our positive relationship with G-d or a friend or spouse, for that matter. Therefore, one does their best to do what they ask, not do what they ask us not to do, and we love them on their terms.