English "each other" is a frozen two-word unit: it never inflects, and it never tells you who the parties are. Finnish handles reciprocity in a completely different way — it takes toinen ("the other, the second"), puts it in a plural case, and adds a possessive suffix that tracks the subject. The result is a family of forms — toisiaan, toisilleen, toistensa — that carry both a case and a person. Where English freezes "each other," Finnish makes it a living, inflecting phrase, and mastering it is a genuine C1 marker.
The everyday workhorse: toisiaan ("each other," as object)
The single most common reciprocal form is toisiaan — the partitive plural of toinen plus the third-person suffix. It is the "each other" that serves as the object of a verb, especially the many verbs of feeling and interaction that govern the partitive.
He rakastavat toisiaan syvästi.
They love each other deeply.
Sisarukset kiusasivat toisiaan koko lapsuuden.
The siblings teased each other all through childhood.
The suffix agrees with the subject just as it does with the reflexive itse. For a first- or second-person subject you change the suffix accordingly: toisiamme ("us, each other"), toisianne ("you, each other").
Autamme aina toisiamme muuttojen kanssa.
We always help each other with moves.
Tunnetteko te toisianne entuudestaan?
Do you know each other from before?
Case follows the verb: toisilleen, toisistaan, toisiinsa
Because the reciprocal is a real inflecting phrase, its case is chosen by the verb or preposition, exactly as a noun's would be. So "to each other," "about each other," "into each other" each get their own case, always carrying the subject-tracking suffix.
| Case | Form (3rd person) | Meaning |
|---|---|---|
| Partitive | toisiaan | each other (object) |
| Allative (to) | toisilleen | to each other |
| Elative (from/about) | toisistaan | about / from each other |
| Illative (into) | toisiinsa | into / with each other |
| Genitive (of) | toistensa | each other's |
Naapurukset eivät ole puhuneet toisilleen vuosiin.
The neighbours haven't spoken to each other in years.
He pitävät toisistaan, vaikka riitelevät usein.
They like each other, even though they argue often.
Kaksi vanhaa ystävää törmäsi toisiinsa lentokentällä.
Two old friends bumped into each other at the airport.
Tiimin jäsenet kunnioittavat toistensa mielipiteitä.
The team members respect each other's opinions.
In toistensa mielipiteitä the genitive toistensa ("each other's") modifies the noun — a construction English can only render with the possessive "'s." As with the object forms, the first- and second-person suffixes exist too: toisillemme ("to each other," we), toistemme ("our — each other's"), toisiltanne ("from each other," you pl.).
keskenään — among themselves
A close cousin is keskenään, an adverb meaning "among themselves / with each other." It comes from kesken ("between, among") plus the possessive suffix, and it stresses that the interaction stays within the group, excluding outsiders. It is neutral, everyday register.
Lapset sopivat asian keskenään.
The children sorted the matter out among themselves.
Puhukaa keskenänne, ennen kuin päätätte.
Talk among yourselves before you decide.
Note the same subject-tracking: keskenään (they), keskenämme (we), keskenänne (you pl.). The difference from toisiaan is one of angle — toisiaan points at the mutual action itself ("they love each other"), while keskenään frames the whole event as internal to the group ("they settled it among themselves").
toinen toistaan — the literary "one another"
There is a more emphatic, somewhat literary variant that spreads toinen across two words: toinen toistaan ("one another"). Here the first toinen sits in the nominative and the second carries the case and suffix. It highlights the reciprocity member-by-member and is common in elevated prose, headlines, and set expressions.
Kilpailijat kannustivat toinen toistaan maaliin asti.
The competitors cheered one another on all the way to the finish.
Onnettomuudet seurasivat toinen toistaan.
The accidents followed one after another.
The last is a fixed pattern — toinen toisensa jälkeen ("one after another") — where the reciprocal template stretches to mean sequence rather than mutual action. In ordinary speech you would more often just say toisiaan; reserve toinen toistaan for weight and rhythm.
Common Mistakes
❌ He rakastavat toisiaan itseään.
Incorrect — don't stack the reflexive on the reciprocal; 'each other' alone is toisiaan.
✅ He rakastavat toisiaan.
They love each other.
❌ Autamme toisiaan aina.
Incorrect suffix — with the subject 'we' it must be toisiamme, not the 3rd-person toisiaan.
✅ Autamme toisiamme aina.
We always help each other.
❌ He puhuivat toisiaan koko illan.
Incorrect case — 'speak to each other' takes the allative: toisilleen.
✅ He puhuivat toisilleen koko illan.
They talked to each other all evening.
❌ Me sovimme asian keskenään.
Incorrect suffix — with 'we' the form is keskenämme, tracking the subject.
✅ Me sovimme asian keskenämme.
We settled the matter among ourselves.
Key Takeaways
- Finnish builds "each other" from toinen in a plural case + a subject-tracking possessive suffix: toisiaan, toisilleen, toistensa.
- The case follows the verb (object toisiaan, "to" toisilleen, "about" toisistaan, "into" toisiinsa, "'s" toistensa), and the suffix follows the subject (toisiamme we, toisianne you pl.).
- keskenään ("among themselves") frames the action as internal to the group; it too tracks the subject: keskenämme, keskenänne.
- toinen toistaan ("one another") is the emphatic, literary variant, and underlies the fixed toinen toisensa jälkeen ("one after another").
- The reciprocal is not a frozen word like English "each other" — it is a fully inflecting phrase.
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- The Reflexive itseB1 — Finnish has no separate reflexive pronoun — itse plus a possessive suffix (itseni, itsensä) does the work of 'myself, himself', while bare itse means 'oneself' for emphasis.
- Declining Personal Pronouns: minä → minua → minutA2 — The case forms of Finnish personal pronouns — genitive minun, partitive minua, the special accusative minut, and the local cases minulla, minulle.
- Reflexive and Automative Verbs: -utuaB2 — Finnish verbs that turn an action back on the subject (peseytyä 'wash oneself') or let it happen on its own (avautua 'open') — and why they take no object.
- Indefinite Pronouns: joku, jokin, moniA2 — How Finnish points at an unspecified someone or something — joku vs jokin, plus eräs, muutama and moni, and the quirk that these pronouns inflect internally.