So I'm writing an original screenplay based loosely on this guy I used to know that was quite a character, and I'm getting a lot of insight about him and his "zany antics" from a friend of mine who spent alot more time with him than I did. Well alot of these antics are going to end up in my script, in fact, they will anchor the comedic aspect of it. My question is, at what point am I obligated to share story credit with my friend even though I will be writing the screenplay by myself? He's not a screenwriter (nor does he aspire to be), but I want the guy to get credit if it's owed to him.