Interesting word, 'No' -- it can be negative, but the results? Sometimes they can be positive...
Your prompt this week, should you accept it, is: Hell, no. Just...no.
That's what one of your fictional darlings is thinking/saying/living this week. Something has come to a head - a relationship once good now gone bad? A job offer/proposal/decision they've been putting off? Someone making a play for someone they adore but have feared to tell about it?
Saying 'no' isn't always negative - sometimes it's about saying no to hesitation, to 'doing the right thing' according to everyone else.
Things are looking grey and difficult, but....one of your characters has had it, and is about to take action. Why's that? What happens next? Do tell!
Happy Monday, and hope you have a good and creative week.