The history books are full of great musical collaborations that have thrived despite bitter personal conflicts: Reed and Cale, McCartney and Lennon, Sonny and Cher. Add to that list teenage Azerbaijani Anar Badalov and his musical life partner, Flora Wolpert-Checknoff, better known as the Baltimore indie-pop duo Metal Hearts. While their long-running rivalry (rooted in a shared crush and years of competition) runs deep, the fruits of their reconciled musical relationship are surprisingly harmonious. While there's nothing metal about Metal Hearts, there's plenty of heart. Electro beats and bleeps add a calculated cool and post-post-modern tension to the band's organic, dynamic sound; its bedroom pop is prone to somnambulism, wandering half-lidded and semi-conscious to the corner bodega, the smoky jazz lounge and the booming club. Like Pinback with some added saxophone squeals and angelic vocal harmonies, Badalov and Wolpert-Checknoff play glimmering, understated masterpieces. Let's just hope they don't start getting along.