With her oversized glasses and geek-girl enthusiasm, Lauren Bird, 22, a recent New York University grad, epitomizes a certain corner of online culture. Once a week, on a YouTube channel run by the Harry Potter Alliance, she posts a webcam video from her bedroom in Astoria, talking in a rapid-fire, fangirl way, using her love for Potterdom to change the actual world.

The future of civic engagement might wind up looking like this: A blend of fact and fiction, channeled toward a cause. If so, its model is the Somerville-based alliance, which connects the feverish online world of “fandom” to what’s known, in Internet jargon, as “IRL” — In Real Life.