
If you have questions about the conjugation of брательник or Russian nouns in general, you can practice and get feedback from a professional tutor.
Слушай, сержант, я надеюсь, ты хорошо за моим брательником присматриваешь?
So sarge, you taking good care of my brother? The first thing I told him was to imagine what you'd do, and then do the opposite.