Yes. First thing to mind are the copyright implications of remixing someone else's character, and the copyright the meme creator gets to the work regardless. Is it explicitly legal to do or is it just that most creates don't care much, what about if you try to earn profit by publishing a book of meme?

Then there are the platforms the meme it is hosted on, is it home hosted, is it hosted on a mega tech site, both of which come with a host of differing legal responsibilities and implications.