When writers (or other creatives) talk about muses it’s in reference to ‘the muse’ – the ‘being’ or thing that inspires their creativity. You’ll often hear writers sighing and worrying that ‘the muse is quiet today’ or ‘my muse has deserted me’. Although ‘muse’ is still in common use today, it’s probably not because writers genuinely believe external forces (i.e. The Muses from Greek mythology) but probably because it’s quicker, and perhaps less depressing, than saying you’ve hit a dry spell creativity and inspiration wise.
We often use the term ‘muse’ while we’re writing or refining ideas. However, our muses are not something separate that helps with our creativity as a whole, no, when we say things like, “the muse is rolling his/her eyes at me for that idea”, we mean that one of our characters’ is being a sarcastic sod towards an idea. Our muses are our characters. We freely admit to dominant and loud muses, versus the quieter ones. Our loudest are always our ‘Emissaries’ muses, who actually have their own separate bits of our shared brain.
Our muses don’t inspire us creatively, per se, – like the usual term for muse – but rather argue and whine at us for attention and plot-line decisions.