A heroic couplet

must be written about a fictional hero.

expresses a complete poetic thought.

is a pair of nonrhyming consecutive lines.

contains fewer than ten syllables per line.

expresses a complete poetic thought.

A heroic couplet must express a complete poetic thought. This is true of most types couplets. This means that the grammatical structure of the couplet is closed. It often contains punctuation that indicates it is a closed idea. A heroic couplet does rhyme and it's written in iambic pentameter. This means that it has exactly ten syllables per line. A heroic couplet does not need to be about a fictional hero, but it does need to be rooted in something heroic like a battle.