During this summer's 'Reflektor' tour, Arcade Fire made a point to play a cover of an artist from whichever city they were in that night. Now that they're back home in Montreal, though, frontman Win Butler wasted little time in demonstrating who's king of his own scene.

Butler strolled onstage during a show by Maryland's Future Islands and joined the burgeoning indie rock outfit for a performance of their single, 'Seasons (Waiting on You),' last night (Sept. 2).

Check out fan-shot footage (via Brooklyn Vegan) below:

Future Islands are in the middle of their North American tour, wrapping up on Sept. 27 in Minneapolis. They then head to Europe through mid-November. Get their full tour schedule here.