My very first written fanfic was a little Harry/Ginny that I wrote back in the day when I was starting out. It was inspired from a scene in another fanfic. The author of the story would never recognize it the way I wrote it. I took a wee idea and made it my own. The general theme is probably cliche and if someone else wrote one like it I would never think it was plagiarism. I would likely be flattered if someone used a spell or potion I created.

As for icons, I try to either make my own or use ones found on free icon sites that don't ask to be credited.