Somerville’s annual “What the Fluff?” festival, which was held in Union Square on Saturday, kicked off on Friday night with a pre-party at Bloc 11 for marshmallow-loving VIPs. The belle of the ball was Susan Olsen of “The Brady Bunch,” who appeared at the festival with her Fluff-inspired art. Hanging with Olsen – a.k.a. Cindy Brady – at the party were Geri Reischl, who…played Jan Brady on the variety show “The Brady Bunch Variety Hour,” and kitsch collector-songwriter Allee Willis, who co-wrote one of our favorite songs, the Pointer Sisters’ hit “Neutron Dance.” She also co-wrote the Pet Shop Boys’ “What Have I Done to Deserve This?” and music for “The Color Purple” on Broadway. …..