Would you keep fighting for your child or respect his wishes?

My son moved in with his dad a couple years ago. There wasn't any big fight or anything that lead to it. He didn't really like living in Arizona and wanted to go to Oklahoma with his dad. He was 13 at the time so I decided to respect his choice. We are now in a CPS case because his step mothers grandfather touched him inappropriately on several occasions. Whether or not his dad knew about it is unclear. My son won't give a real answer on that. I've been fighting for custody of him and have another court date the 8th of August. Back in June my son was saying he wants to come live with me and he doesn't want to live with his dad anymore and was begging me to fight for him. Well we had a court date this month and he did a whole 180 and is now saying he wants to stay with his dad. He isn't telling me why he wants to stay with his dad. Just now he doesn't want to leave. Which was weird because before that he was begging me to plz take him and he wants to come with me. My brother thinks maybe his dad and step mom said something to him. My brother is my lawyer and said that since my son is nearing 16 the court will take what he wants into consideration however if they truly don't believe staying with his dad is in his best interest they won't keep him with his dad regardless. If you were in my situation would you do what your child asked you to do the first time which is fight for them or respect their new decision?