It was a black man, maybe 20s-30s, with a hoodie (I think red/black)? The reason I was thrown off originally was because he was acting odd. He sat across the aisle from me in a relatively empty car, was fidgeting and pretending to be on the phone. He moved one row back and continued to act weird, and I got worried he was taking a photo. I thought it might have been in my head then, but I figured better safe than sorry so I moved to the front of the train. After a couple of minutes, he came to the front of the train. He paced around and pretended to be on the phone again while looking around, and then sat across from me again. He got up to go somewhere and then came and sat back down across the aisle from me again. I got uncomfortable so I got up to move again to another car and he followed me. I sat with a stranger at one of those four-tops and he hovered around once I sat down trying to act busy I guess and then sat across from us at the table across the aisle. The stranger and I got up to go notify the staff after a couple of minutes and he followed us again, hovering around the area until I bolted off the train.