Complex sentence: The four bonded over their mutual affection for 1990s music, the Riot grrrl movement, and Kevin Costner's Waterworld and started making music together, performing at small shows and releasing singles.
Split into simpler sentences: The four bonded over their mutual affection for 1990s music, the riot grrrl movement, and Kevin Costner's "Waterworld". They started making music together, performing at small shows and releasing singles.