So in my most recent campaign I have planted a NPC droid companion in the party to act as a ally and to nudge the players in the right direction until the "new group syndrome" wears off and they do so on their terms. He's a K2 droid who got most of his memory fried in a midlife crisis and is looking to seek his way in the galaxy. Since the PCs are rebels he will be assisting them and I hope he will grow on them. He'll be that badass guy who does no look kills and say some quippy droid one liners and over time I hope that the PCs will grow quite attached to him.

However he is using the PCs and the rebellion to relearn about the galaxy and establish connections. While he certainly does not like the empire, he sees the rebellion as a fruitless cause and a means to an end. Luckily a-lot of the campaign will be in the CSA so theres plenty of opportunities to be bought. He will betray the PCs and bring about a serious spanking of their rebel forces midway through the campaign. He then will receive some favor and leave to be a independant mercenary or perhaps join a existing seedy organization. Any tips on how to do it? How to twist the serrated vibroknife? How to make a moment memorable and the PCs clawing for revenge?

The first step is to make the droid NPC indispensable and completely trustworthy. To set up a 'proper' (?) betrayal you have to be completely trusted. So start by making the NPC reliable and effective at what the PC's want it to be good at.

As for the actual betrayal scene, if the droid is a reliable trusted member of the group, the betrayal will seem like its coming out of left field. And THAT is what will make it all the more jarring.

"Wait? What?!?! Dr Yu! How could you! You obviously HATE the Harkonens! NOOOOOOOOO."

Betrayal is something with pretty starkly inverse appreciation from GMs and players. It can be pulled off, but I'd throw out the general caution not to take it lightly, as it can easily come across as GM fiat -- or worse, predictable GM fiat, like you've been rubbing your hands for this moment more than one generated by the players' actions.

The betrayer needs to evoke emotion of some kind, which you understand with your two mentions of it; if players don't care, scrap the idea for that NPC. I'll take a different perspective and recommend that you need players to be able to look back and see the path to the act, however subtle. Arbitrary character shifts are cheap.

Plus, in my experience, you don't need a light-to-dark reveal. I ran an indirect betrayal in which the party stumbled on the group hit of an outfit they liked by an outfit they didn't like, and an amoral but calculating/gladhanding employer of theirs. The hitters' leader went from rival to villain, while the party waited several sessions to meet with the employer, even after I'd telegraphed that the hit was just business and no enmity existed between them and him.

So, yeah: guide this one in like a runway landing, making adjustments as you go. Find out what gets your players going and work from that.

One other thing: when betrayal occurs, make the situation complex enough that players have agency. If it looks like doomsday but you've factored in the party's potential to mitigate some things, players are a lot more likely to buy in.

On 1/29/2019 at 10:03 AM, wilsch said:

Betrayal is something with pretty starkly inverse appreciation from GMs and players. It can be pulled off, but I'd throw out the general caution not to take it lightly, as it can easily come across as GM fiat -- or worse, predictable GM fiat, like you've been rubbing your hands for this moment more than one generated by the players' actions.

The betrayer needs to evoke emotion of some kind, which you understand with your two mentions of it; if players don't care, scrap the idea for that NPC. I'll take a different perspective and recommend that you need players to be able to look back and see the path to the act, however subtle. Arbitrary character shifts are cheap.

This.

Extreme Caution is required. After the betrayal is revealed, the first instinct will be to cut ties with the traitor, which make for a boring story going forward. Thus, I would never use a mere droid as a turncoat. I would recommend someone very close to a PC to make the sting more painful, also give a reason for the PC to hang on to him (at least emotionally) until they meet again -- and they should meet again, because this story has at least three beats to it: betrayal, argument then resolution.