Remember that “other’s” is the correct singular plural form of the base form “other.” “Each other’s” is the correct form we use to refer to one. To remember the form to use, simply remember the inclusion of “each” means it is singular.

Because we have prefixed “other” with “each” it has to remain in the singular form. While there is a plural form for “other” which is “others,” it differs from the example of “people” since it has no alternative meaning and cannot be pluralized yet again.

However, you should point out to students that each other is treated as a singular pronoun and emphasizes two or more separate people. Each other’s is always correct, and each others’ is never correct.

It is important to note that ‘each other’ is always used as a singular pronoun. This means that it should always be followed by a singular verb, even when referring to multiple entities.

"Each other" refers to a singular subject, just like "one another" does. Notice "each" and "one" are singular; so are "other" (an other v. others) and "another" (which is like a contraction or compression of "an other").