Thank you all for the feedback. I imagined myself rewriting the idea in my own words but often come from inspiration of people’s ideas I see online. I rarely have original ideas of my own.
It really depends on how generic it is, too.
A slave x master plot that doesn't have any sort of plot behind it beyond just the pairing being listed can be taken word for word. Nobody owns the rights to putting ''slave x master pairing'' in their request thread. On the other hand if it includes very specific things, obviously that's an original concept (insofar it can be, everything's been written at least once
) and can't be taken word-for-word. I'd PM them, ask if you can take it and change it to fit your own needs, and if they say no, then I suppose you'll have to take a no for an answer and find a way to take the same key concepts you're interested in and write about them.
In the end, if you can deduce from an idea what you like about that idea, I feel like it'll be hard for someone to stop you from writing about an interest you both seem to share. If I have an idea on my request thread about a barbarian and a healer who go through a trial together and emerge victorious, winning the Adventurers World Cup in Adventuring (AWCA for short), and then they go on to get married and suddenly there's a murder they need to solve, you can easily deduce that the elements you like are the fact that there's a tank and a healer, there's some sort of struggle they go through with a prize at the end, a marriage and then a murder mystery.
Nothing stops you from then creating an idea of your own that incorporates those elements while being distinct and different enough that it's not really my idea anymore. If you change the setting to be in space and change the order of events, or combine things, etc. it's not even close to my idea anymore and I'd have no right of really complaining about it, I guess?
That's just how I'd approach it though.