So recently I've been a player in CoS and while that game has no bearing on this post it is the inspiration of it. You see, I've been working on my homebrew world for a little under 2 years now and those that have daunted the task know it is not easy.

As I'm coming to a close I've been focusing more on the narrative of the world, possible plot points for my players and the what ifs. Sure I may have gotten a little too far ahead of myself, but this is what's been on my mind lately.

In one of Matt's videos, he spoke of a player's long term goal of assassinating a Wizard and he did so by impersonating a King or something along those lines. When they finally found the Wizard the characters first action was to kill the Wizard, effectively revealing he was a traitor for the Thieves Guild the entire time.

My question is, should I as a storyteller/GM encourage on if not all of my players the opportunity to have some unknown goal (to the other players) that if accomplished would effectively betray the party. Should I encourage one player secretly like Matt's story did or for those that watch Critical Role, do something similar to what Liam O'Brien did in his one shot and give each of them a goal. Or at the very least a majority of them.

Your thoughts on the pros and con, as well as your experience in doing something similar are very much appreciated.

Thank you for your time. I look forward to learning from your comments.