so as you save more and more people from the Puppeteer, they form an audience for your fights, they can throw items and stuff
during the Fantoche fight, they yell rhyming cheers in sync with the music to boost your confidence
and when Fantoche begins preparing his special attack, RGB Laser, he starts making color puns, and the audience goes "Color puns? That's it, we're done! Maybe in the old fight they woulda been fun!"
(a reeeaaally old game idea of mine featured a Fantoche boss fight where he manipulated your color pallette, changing your emotion and the way you fight)