Allegedly "shrouded in mystery" despite a social media presence (with accompanying photos) on Twitter, Tumblr, Facebook, Soundcloud, and YouTube, as well as major support from fellow Torontonian Drake, alternative R&B act the Weeknd -- a solo outlet for vocalist Abel Tesfaye -- surfaced in March 2011 with House of Balloons. A nine-track, 50-minute mixtape made available for free download on the Weeknd website, House of Balloons was based in morose ballads filled with drug references and…