Reciprocal jedan drugog

Themselves, or each other?

You already know verbs with se: Marko se brani — Marko defends himself. Now put two people in the subject: Marko i Ivan se brane. Does each defend himself, or do they defend each other? From the sentence alone you cannot tell — se covers both. With many verbs the context settles it (Ana i Marko se vole is almost always 'love each other'), but often you need to say it outright.

Serbian says it outright with jedan drugog — literally 'one ... the other'. Marko i Ivan brane jedan drugog can only mean they defend each other. Doing something to each other, where every person is both the doer and the receiver, is called reciprocity.

The two halves behave differently

This is the whole trick. The first half, jedan, is the doer, so it stays in the nominative, the plain dictionary form, every time. The second half, drugi ('the other'), is the receiver, so it takes whatever case the verb or preposition demands — exactly the case a noun in that position would take.

• voleti, razumeti, poštovati, podržavati take a direct object (accusative): vole jedan drugog
• pomagati, verovati, pisati, oprostiti, nedostajati take the dative: pomažu jedan drugom
• s(a) takes the instrumental: svađaju se jedan s drugim
• na, bez, o take their own cases: oslanjaju se jedan na drugog, ne mogu jedan bez drugog

A preposition goes between the two halves, never in front: jedan s drugim, jedna na drugu, jedan bez drugog. Saying s jedan drugim is the classic beginner slip.

Who is involved decides the gender

Both halves agree with the people involved. Two men (or two masculine nouns) take the masculine jedan ... drugog. Two women take the feminine jedna ... drugu. A man and a woman together — a couple, parents, a brother and sister — take the neuter: jedno ... drugo. The neuter here is not about things; it is how Serbian handles a mixed pair.

Gender comes from who the people are; case comes from the verb. Ana i Mila are two women, so it is jedna, never jedan. And if Ana's partner is Marko, the pair is mixed: Ana i Marko vole jedno drugo, not jedan drugog.

For a larger group the plural is also used: jedni druge, jedni drugima, jedni s drugima. Komšije pomažu jedni drugima — the neighbours help one another.

Verbs that are already reciprocal

Some se-verbs can only describe something two people do together, so se alone is enough and nobody adds jedan drugog: upoznati se (meet, get to know each other), zagrliti se (hug), posvađati se (fall out), pomiriti se (make up), dopisivati se (write to each other). Upoznali smo se na fakultetu — we met at university. When such a verb names the partner, the partner comes with s(a), and that is where jedan s drugim appears: dopisuju se jedan s drugim.

međusobno — 'mutually'

The adverb međusobno ('mutually, among themselves') also marks reciprocity, without changing for gender or case. It suits groups and slightly more formal speech: Komšije međusobno pomažu. Its adjective is međusoban ('mutual'): međusobno poverenje — mutual trust.

To keep 'each other' apart from 'themselves', remember the pair: sebe points back at the doer, jedan drugog points across to the other person. Ne kritikuju sebe, nego jedan drugog — they don't criticise themselves, they criticise each other.