Let's be honest, half the fun of running games in an established universe is all the shared references that can be used. If you're running Star Wars, you can get a lot of mileage by pulling references from the movies. You don't have to tell someone what a lightsaber looks like, or sounds like, because your players have probably seen the movie. That shared reference point helps pull everyone into the game, and things get better. However, when handling the established characters of a universe, things get tricky. After all, those characters are likely the Big Time (yes, capital letters) heroes of the universe, but the story is supposed to be about your PCs. Today, we're going to look at how to handle that.
Big Time Heroes
You know what the problem is with bringing Luke Skywalker into your Star Wars game? Honestly, he's kind of a big deal. He's a big time hero, the last of the jedi, and the personal savior of the galaxy at least 20 times over at this point. If your players kill him, the whole universe goes out of whack in a very real way, and it is next to impossible to outshine him without some heavy GM work. Even worse, a lot of people (particularly GMs in some cases) won't want to do this, because it can change the feel of the game and the world in strange ways. These are the key problems I am going to try to help address.
Treat Them Like Spices
The big trick to handling these characters in your game, is to treat them like spices when cooking. Now, some people like a lot of spice, others prefer a little, but you know what both camps have in common? They don't want the spice to be the majority of the meal. Spices add flavor and texture to a meal, they do not comprise the meal itself. This is what you want to do with these characters. If you're running Halo, it is cool to have the Master Chief show up. Hell, it is even cool for him to be a major factor in a story line or two (especially if your players want him around more), but he shouldn't be there for the whole game. The players need time to shine, time to establish themselves, and just time to be the main focus of the game.
Using these big time characters requires more planning on your part. For one, you need to know what they're doing in the area, and how they are going to interact with the PCs, and all that other stuff. One of the things you will likely want to do is give whatever the PCs and this big time character are working on a forked objective. The big timer goes off to handle one, the PCs handle the other. This way, the game can focus on the PCs heroics, but the big timer is still being helpful. Still, these things take time and planning, so put the time in. Trust me, your PCs will know when you are improving while playing with the universe's big players.
Know The Character
One of the fastest ways you can ruin the feel of an established universe is to fuck up one of the big stars of it. Think about it, would Halo feel like Halo if the Master Chief backed down from a challenge? How about Star Wars if Han suddenly lost his heart of gold, or didn't have a quick quip ready on his lips when things got rough? This is another reason to keep the big characters in your game to a minimum (and used only for added flavor): everyone has their ideas of how they are and how they interpret them, and it is easy to get that wrong. Also, there is always a chance that someone in your group knows more about a particular character than you do, which can make them even easier to betray. It can be annoying to have someone interrupt your RP as a big character with something like "Yeah, but Adama would never do that!"
Let The PCs Shine
It can be tempting to show off how powerful the main character from the movie is. And they should be powerful. Hell, if I'm playing in a Power Level 12 DC Adventures game, and Superman shows up, I expect him to be bigger and more badass than me. He's a higher level, and frankly, he's Superman. However, that doesn't mean that he should completely steal the show. I should have my moment to shine - I'm a PC after all - as should the rest of the PCs. Superman can help, he can even be a big help, but if he is the reason a fight is won, and it is the climactic fight for a story line, than you have failed as a GM.
So, how do you handle this? Well, honestly it depends. Mostly, I do it by having the big NPC doing some heavy lifting, but the actual deciders of how the event plays out is up to the PCs. In one Supers game I ran, the big time heroes didn't show until the shit had really hit the fan. Like, we're talking a 200 metahuman brawl going on. In the chaos, all the big heroes were lost in the fray but they gave an excuse for why the PCs weren't having to deal with all the top tier villains yet. The PCs decided the fight, the big time NPCs bought them time. They were a huge help, but the PCs were still the heroes.
This is one of the reasons I recommend to stay away from established plots and storylines. Running the Battle of Endor sounds cool and fun, but we all know how it ends. Luke duels Vader in the throne room, Han leads the ground assault and Ewok ambush to get the shield generator down, and Lando and Wedge lead the attack into the Deathstar for the kill shot. Unless you're looking to majorly change things by messing with that, those events are set in stone. So, why not instead set events up away from the movie story where the PCs can be the big time heroes. It is a game about them after all, right?
If You Have To Use The Big Story
If, for whatever reason, you have to use the set story, then you need to work even harder. For one thing, unless you want to royally change the events that happen, you need to find a significant way for the PCs to effect things without changing the established canon.
An example for this (to keep going back to Star Wars) would be to have the PCs, at the Battle for Endor, have to infiltrate and sabotage the Executor during the space battle. It's a desperate move, but needed if the rebellion has a chance. If the PCs succeed, then they are why the shields go down and enables the crashing A-Wing to hit the bridge and crash it into the Death Star and strike that needed blow. The PCs are heroes, right up there with all the big NPCs for winning the battle, but you haven't changed anything. You've added to the mythos without changing, and that is a hard thing to do.
My main point here, I think, is that using these characters can be done well and really add a lot to your game. However, you want to use them carefully. Small brushes to show how the PCs are coming along (or even to show them growing as they catch up to the movie/book heroes) can be great, but the longer the big NPC is on stage, the more they're going to steal the show. This is fine if that is what your PCs want, but make sure it is what they want first.
Any other advice for handling these characters? Sound off in the comments.