What is the word for when someone rides behind you on a horse?

There isn't a single, universally accepted word for someone riding behind you on a horse.

However, depending on the context, you could use:

* Follower: This is a general term for someone who follows you.

* Escort: This implies someone is accompanying you for protection or guidance.

* Rear rider: This is a more literal description of their position.

* Second rider: This is a more specific term if there are two riders.

* Trailing rider: This highlights the fact that they are behind you.

The best word to use will depend on the specific situation and what you want to emphasize.