Uh, if you're doing it for free, you can do whatever the hell you want xD

I mean the only exceptions I can think of are like... if you're doing anything with someone's character that might make them uncomfortable like nudity/violence/sex etc like those would be good to ask about subject matter before you draw it and/or check in with them before you post it publicly?

But otherwise you're doing a nice thing because you're nice and you're under no obligation to do it any particular way. :3

I'll run with that. I like it. Thank you <3