Bad idea. That's too much of an age difference for legal reasons. The 21 yr old guy could run into problems with her parents.
As soon as anything goes south, her parents may threaten to call the police. Even if it's just because they don't like something you said or did. I would ask her parents for permission first.
Then go off of that. Honestly, I wouldn't do it. Just find someone else.
I cant really gove you an answer,but what I can give you is a way to a solution, that is you have to find the anglde that you relate to or peaks your interest. A good paper is one that people get drawn into because it reaches them ln some way.As for me WW11 to me, I think of the holocaust and the effect it had on the survivors, their families and those who stood by and did nothing until it was too late.