Russian Possessive Pronouns

Did you know that the Russian position pronouns eё (her), его (his, its) and их cannot be declined. You don’t have to add an н to them before prepositions.

For example,

1. Я завтракал с её братом (not с неё братом). I had breakfast with her brother.
2. Мы ездили в Москву и жили в его доме. (not в него доме). We went to Moscow and lived in his house.
3. Серёжа думал об их книгах. (not о них)  Seriozha was thinking of their books.