Well writing for Penny is not very hard since she acts so human like if not for a few hiccups here and there. I find you just have to follow the rules you would with any other character and that is figuring out their personalities features. In Penny's case if we are following the cannon we know that she is fairly polite, excitable, and a bit naive. She also values friendship a great deal and would fight to protect it.



As for back story well that can be a hard one. She has no real backstory in the cannon other than she was built by an unknown professor who she calls father. We know that father is a fairly protective creator. We can guess he cares for Penny like a real daughter but I have seen writes go a different with it. We also know that she was funded in part by General Ironwood. It seems the General wants to use her as a weapon so I have seen him play the villain a few times but. Ironwood does not seem to be an heartless or evil man but rather a man who would do whatever it takes to defend the people. Of course he may not count a robot as being a member of that group.



These points in which I see most writes use to write a backstory for her. I myself have focused more on the present so far in my story. By the way where do you post your work? I wouldn't mind checking it out when I have some time. I post all my work on Fanfiction.net and Archiveofourown.com as just Sillva.