“Each others” is used when you’re referring to the plural form of “each other.” However, there is no plural form of “each other,” so “each others” is actually an incorrect term that can’t be used. “Each other’s” is used when you refer to the singular possessive form of “each other,” which we’ll touch more on later.

Think about it like you are referring to “each other” (singular). In that case the word “other’s” is correct. It is like you are saying “each other’s.” With the plural form being others’.

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.

The rule is that “each” will always be followed by a singular. “John and Mary promised to love each other forever. They agreed to take care of each other’s wellbeing above all else.” The apostrophe is used to indicate possession, and it comes before the s, not after it. If we don’t prefix “other” with “each”, we can use it in the plural form.

There is a camp of prescriptive linguists who insist that there is a difference. And that difference is: “Each other” should only be used to describe two individuals, while “one another” should only describe three or more.