Currently I am studying English in a school, and today I had an exam, and one question was like:
"What did your brother use to do when he was 5 years old?"
My answer was:
"He used to fight me a lot, when he was 5 year old"
then she told me "that fight me" was wrong that I needed a preposition, so I used "fight against me" in the sentence, she said that the sentence was correct now, but I have doubts, and I think both are fine written.