The early Dinosaur Jr. were defined by two qualities: volume and volatility. The stewing bitterness between guitar-slinging introvert J. Mascis and bass-pounding extrovert Lou Barlow resulted in some of the most frazzled and ferocious music of 1980s indie rock. The acrimony was so deep-seated that, even after Barlow's exit in 1989, he went about writing spiteful songs about his ex-bandmate like Taylor Swift writes about ex-boyfriends.