Much of the early Odd Future buzz centered around Earl Sweatshirt, whose video for “Earl” was a teen-rebel fantasia of drug use and other misbehavior. A provocateur with a dry wit and an outrageously dexterous gift for wordplay, he was a clear inheritor of Eminem’s macabre humor and Lil Wayne’s dyspeptic logorrhea. He was a savvy, schooled rapper: gross, entrancing and thrilling. And also one of the only pop mysteries left. By the time Odd Future began performing and doing interviews, he was nowhere to be seen. In a time of Internet-speed information flood, Earl Sweatshirt’s absence — he was sent to Samoa by his mother — a striking rarity.