As heirs apparent to the throne of '90s alt-rock, Kurt Vile and Courtney Barnett appear to be an ideal match -- comrades in slacktivism united by a shrug and a smirk. If neither singer/songwriter sounds precisely like the other, they're good complements, both cherishing laconic melodies, loping rhythms, and a loads of guitar. All of these elements are in play on Lotta Sea Lice, a rambling nine-song affair that finds the duo singing each other's songs, playing tunes penned by friends, and covering Belly's "Untogether," an underappreciated '90s cult classic that the band once played as a duet with Radiohead's Thom Yorke. Barnett and Vile do not bring to mind Yorke and Tanya Donelly, nor do they sound a thing like the original Kurt and Courtney of Nirvana and Hole fame. Singing together, Vile and Barnett evoke J Mascis and Liz Phair, comparisons that have been leveled against the individual rockers before, but on this lazy stroll of an LP, it appears the pair are indulging in alt-rock cosplay. It doesn't help matters that when they indulge in an explicit duet, they often veer toward the cutesy, as on "Continental Breakfast," where they puff up their international friendship over the titular meal. Food is a problem with Barnett and Vile: "Blue Cheese," one of the sprightlier numbers here, is undercut by a performance that suggests the pair know precisely that it's hookier than the rest of the proceedings, as they lean into a "nanny nanny foo foo" lyric just a tad too hard. Usually, though, Lotta Sea Lice just settles into a cozy rustic groove that dispenses with any of the coiled energy of Barnett's Sometimes I Sit and Think, and Sometimes I Just Sit. and opts for Vile's cheery stoner strumming. As they're both charismatic singers with a way with an elliptical melody, it's pleasant enough, but by the time its 45 minutes wrap up, Lotta Sea Lice feels like a party where the hosts are having a much better time than their guests.