How do I say “with someone” in Finnish?

Miha asks:

Hey, I’ve been trying to understand this for quite some time now, if I want to say “with my dad”, then how is genitive formed? Isänin kanssa? Mun isän kanssa? It’s the -n ending that confuses me here.

My answer:

Thanks for the great question! Combining possessive suffixes and genitives in Finnish is a confusing topic. As you already know, kanssa “with”, needs to be preceded by the genitive case:

isän kanssa

with father

When you want add “my” to this, to say ”with my dad”, you have a few different options:

mun isän kanssa – with my dad, spoken, informal

mun isäni kanssa – with my dad, spoken, more formal

isäni kanssa – standard written

minun isäni kanssa – written, emphasizing the “my” (with MY dad, not yours)

However, when you add a possessive suffix -ni, no further transformation is required with kanssa:

isäni kanssa

If you’re not using possessive suffixes, you need the genitive:

mun isän kanssa

This also goes for other situations where you would normally use the genitive, possessive suffixes are enough on their own:

isäni polkupyörä= mun isän polkupyörä = my father’s bike

Näetkö isäni? = Näetkö mun isän? = Do you see my father?

I hope this helps!