Is there anything wrong with this sentence - Karen smoked and I watched her as I opened up the balcony to let in some air. I write fiction and I use sentences with two subjects with an 'and'?

No there is nothing wrong with that sentence because it has a dependent and a independent. That means that is a compound sentence. If you look up on google simple and compound sentences you will get your answer.

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.