Breakdown of Этот кот ничей, он просто здесь живёт.
кот
cat
здесь
here
он
he / it (for a masculine noun) / it (for a neuter noun)
этот
this [f: эта, n: это]
Questions & Answers about Этот кот ничей, он просто здесь живёт.
Why isn't there a double negative in this sentence? I thought Russian negative pronouns always needed a 'не'.
You usually need a double negative (like я ничего не знаю). However, in the first clause, the present-tense verb 'is' is omitted, as is standard in Russian. Because there is no verb present, there is nothing to negate with не. The negative pronoun ничей simply acts as the predicate: 'the cat is nobody's'.
How would this sentence change if we were talking about a female cat (кошка)?
The pronoun ничей behaves like an adjective and must agree in gender, number, and case with the noun it describes. For a female cat, the sentence would become: Эта кошка ничья, она просто здесь живёт.
Could I use the other lesson word, никакой, here instead of ничей?
No, because they answer different questions. Ничей specifically means 'nobody's', answering the question чей? (whose?). Никакой means 'not any' or 'no kind of', which answers the question какой? (what kind?). If you said никакой кот, it would mean 'not any cat'.
Why do we use он (he) to mean 'it' in the second half of the sentence?
In Russian, the pronoun used for 'it' depends entirely on the grammatical gender of the noun being referenced. Because кот is a masculine noun, you must use the masculine pronoun он, even if you might call an unknown animal 'it' in English.