Is this a bug? I got stuck on another player

[Russell Crowe]

I was fighting a boss at one of the towers with a friend and suddenly i started losing control and then I got stuck on them as if they were giving me a piggyback ride. I could still aim and shoot but had to go where they go. Could this be some sort of Curse that we accidentally picked up, or is this a bug?

Only way I could get it to stop was if he brought me to a catapult and I used it (didn't work if he used it), but as soon as I met up with my teammate I was stuck on them again.

[Ctruth]

Tether perk

[TwitchyBait]

There's two perks that say "find the destined one" if you both get it the second person that gets it is drawn to the first when they get close and rides their back until the first player is either killed or transports to hell (then immediately is drawn back once in hell or that player is ressurected.)