i cant get sued because im not doing it for profit plus im gonna add credits
For clarity by IP I mean Intellectual property.
Without a signed paper saying that you have a license to use anything of that IP they can sue you whether it's for profit or not. While this does vary country to country, you need to be aware that you can't just start using characters from another IP because you are infringing on copyright / IP. The only person who is allowed to make derivative works is the owner of the copyright / IP and anyone who has a license to work with the copyright. I'm not saying that they are going to immediately sue you the moment they find you, but this is a very real possibility and you should consider it.
I recently had a class on this whole ordeal for my game design course and it's a really messy business if you start to forget with it.