Usually an annoying person who:
1. either decides to plan a vacation just like yours so he/she can go with you.
2. you coincidentally encounter during your vacation and forces you to make plans with them for the rest of your vacation.
Joe: Hey, I heard Alfred followed you to the Bahamas.
Henry: I was taking my wife on a vacation so we could spend some intimate one-on-one time with eachother but then he popped out of nowhere. I spent the next two weeks hanging out with him.