Guild Wars 2

I’ve seen folks from the same guild in hotjoin events and I know that once they are in the same instance they muck about with joining the other side until they are on the same team. But how’d they get into the first instance in the first place?

Me and buddy have tried several servers, full, deserted, partially populated and I never see him pop up in the instance.

Get in a party. Make sure you both have yourselves added to your respective friends list.
One of you guys needs to go to the hotjoin browser, find a reasonably low-populated server (so that you can both get in), and enter it.
Right click his name -> Join friend in sPVP.

(Tournaments are a little easier, you just need to queue up with your friend.)

-Turn game notifications on
-add to friends list
-click on notification when he joins a pvp game