Music genre associated with the tellum, or reverse mullet

EMO

This emotional 2000s music style often features dark lyrics and dramatic hairstyles.

The clue references "tellum," which is slang for "emo" spelled backward, hinting at the music genre. The "reverse mullet" part plays on the stereotype of emo hairstyles, often longer in the front and shorter in the back. Together, these clues point to "emo" as the answer.