For whatever reason, the Endermen in my survival world specifically go after a specific friend.

At first we thought it was bad luck, but then it occurred over 20 times, well, at least 20 I could remember. No Enderman visible, then all of a sudden he'd be targeted and attacked.

In some cases, I'd see the Enderman prior to them attacking my friend.

It's not a problem with the Enderman in general, since my interactions with them have ran as expected. But so long as he's in the world, it continues to be a problem.