Which sentence uses correct punctuation and capitalization within parentheses? my brother (he has read hundreds of books on the subject.) told me that the samural lived by a strict code of honor. my brother (he has read hundreds of books on the subject) told me that the samural lived by a strict code of honor. my brother (he has read hundreds of books on the subject) told me that the samural lived by a strict code of honor.

My brother (he has read hundreds of books on the subject) told me that the samurai lived by a strict code of honor.

Parenthetical phrases that interrupt a sentence are not to be capitalized unless they start with a proper noun. They also should not have ending punctuation inside the parentheses. Although the phrase inside the parentheses could qualify as a full clause on its own, in parentheses it is merely a phrase which interrupts the actual sentence by adding additional information, and should therefore not be treated as its own sentence grammatically.