Reciprocal Pronouns in English

Each other and one another are the reciprocal pronouns in English. Typical examples of reciprocal pronouns.

In English, a group of reciprocal pronouns is represented by only two phrases: each other and one another. They express the mutual action or relationship. The object they belong to should always be plural.

Examples:

Though they had to live together, it seemed they hated each other.

Brothers should help one another no matter what.