It was copied from another article on this site. Is that still an issue? If so, sorry. It didn't occur to me. It was a paragraph on the character's bio that covered the part of the plot synopsis I wanted to add and thought adapting it would save time from writing the same thing in different words.
In regard to Wikia's Terms of Service it's an issue whenever someone else wrote it and you attempt to make little to no changes and pass it off as your own work.
That being said, it appears to be an honest mistake, and although it's always best to rewrite summaries in your own words, in the future if you do copy from one article on this site to another for some reason, just be sure to credit the source article in the edit summary.