The words that express mutual actions or relationships
Reciprocal pronouns indicate that two or more people/things are performing the same action mutually or experiencing the same relationship. English has two primary reciprocal pronouns:
Modern usage often blends these rules, but distinctions remain in formal writing.
While traditional rules distinguish based on number, modern usage accepts both forms interchangeably except in highly formal writing.
The apostrophe always comes before the "s" ("each other's" not "each others'").
Convert to reciprocal constructions: