Last Friday I had a player in my game who was only going to be there for one session. I decided to use the session as an opportunity and wrote up a special character for the player to play. The idea would be that the character would show up and be like a Guest Star character in a serialized TV show. Someone who could maybe show up again later on - if the fans demanded it - and who would, in the TV show, be played by a visiting/guest celebrity. The end result worked out fairly well, but as I had some requests to go over it in more detail I figured I'd share those details today.
A Familiar Face
Before I go in to the set up for the character and game that I think helped this work out I feel I should point out this out of character factoid: the player in question is not a stranger to the group or the game. In fact, the person in question was a part of htis game up until recently when he moved out of the area. As such, while still counting as a guest star, it was more like when an actor who used to be a main hand in the show comes back for a one or two off. A bit weirder here as he was playing a totally different character, but still a factor. I mention this because even with everything else going right a strange person to the game could still make things weird.
The Set Up
The OOC note out of the way, the main part that helped this work was the setup. The session was planned and set up to have a heavy focus on this character. I exploited several of the setting's rules to help out with this, and relied on my players to do the rest. For one thing, the guest star character was an Imperial of a higher status than the players and with a job that answered to a higher authority. Now this is a recipe for the character to run roughshod over the other players and be in charge (part of the point, but still needs mitigation.) That fact is mitigated by the character being in the PCs' backyard and not knowing the area.
So what we end up with is essentially a Federal agent ending up in a city they don't know and being assigned a group of local cops to help with their investigation. The Fed is the focus for this, they get to be present, in charge, and feel self-important but they are effectively powerless without the local cop support simply because part of what they need involves knowing the area, which they just don't know. This also sets up a power dynamic (and struggle) between the characters. The Guest Star gets to be important. The normal PCs get to see how they fit into the world as a whole and what power they may hold that isn't always present. I'm not sure how well that came across in the game, but it was part of the idea.
Preparing For The Game
With the plan in place what we then need is to prepare for it. First, foremost, and most importantly I talked about the character with the person who was going to be playing them. I talked to them about who the character was, where the character was coming from, and - most importantly - what I needed from the character.
This discussion about expectations is important. I can't emphasize that enough. Why? Because the Guest Star player isn't a normal player in the game. they're not going to be here all the time. In fact, they may never be around again. They get special perks (being an Imperial, status, higher power level) that comes with the job, they get a session dedicated around keeping them entertained, but they also need to help out with the game as well. In effect, they become a super glorified NPC. Just like in the Guest Star TV shows the purpose is to help show some element of the world that hasn't been present, or to show a different angle of the characters. This conversation lets you get on the same page with the player and talk about what you need, what you want, and what they would like to do. It also gives the player a chance to be a mini-GM for a bit, and for you to bounce ideas off of them to see what works and what doesn't.
Stay On Your Feet
Even with the set up and the preparation you have to understand that no plan survives contact with the enemy. Not that your players are the enemy but they are going to mess up your plans. The player of the guest star can also have interesting interpretations of how to do things. Stay on your feet, stay ready to react, but let the game flow. Trust the guest star to do their job. trust the players to play along. Try to relax. A lot of times these type of sessions are so focused on interaction between the characters that the GM gets a bit of an easier day. Enjoy that, but don't relax too much. You're still GMing a game, and there is one more player than normal.