Let's get off the "players speak up and do something, GMs recognize what the players have done" train for the week and go back to some other advice. There is a piece of advice for writing that can be interpreted in a lot of ways. The advice is simply: kill your darlings. Simple, but also vague right? What it means is that for your story to be stronger you need to kill anything that exists in the story just because you like it. If the only purpose a particular sentence serves is that you like it it needs to go. The same is true for any scene, character, action, or exchange. It's decent advice, but not the way of interpretation I want to talk about. Today I want to talk about how killing darlings in your game can bring the story, adventure, or villain to the next level.
By killing darlings for your gaming table I mean killing - or destroying, erasing, whatever - the things that your PCs love in character. Putting a PC's girlfriend or boyfriend in danger, blowing up the pilot's plane, shooting up another PC's house, hitting them where it hurts. That's right, this is just another way of taking John Wick's "play dirty" advice to hit your PCs where their character sheet can't protect them. But how do you do that?
First We Need Darlings
The first thing we need in the game is darlings. This is pretty self explanatory because if you don't have any darlings then you can't kill them now can you? So how do we get darlings? Well, that's going to take some time. It is also going to take observation. Finally, it's going to take persistence. See, you can put water in front of the horse but you can't make it drink, and until the horse drinks you don't really have anything.
So what do you do? Well, start with planting things there for the PC to like or want. The girl, the boy, the land, the tavern, the magical item. Just start planting things around and see what the PC gravitates towards. When he does, test him a little bit. Maybe he wants to seduce the barmaid, only the barmaid has been hit on by every adventurer that's come through the town and she lives on the borders of Dungeon Ville and Monster Land. So, instead of just going with it she flirts with the PC and then says she'd be happy to go on a date - or whatever - but she'd like the PC to prove himself by handling something.
The something in question is a small adventure. There will be compensation as well (beyond the date) so this can even work as an adventure starting off point. The point is once the players have done the action - if they even do the action - watch the reaction. Does the PC go back to the barmaid to collect their date? Do they not care? If they go back you may have them. Continue the relationship, let it linger, and have the relationship be a positive thing for the player (provided they are treating the NPC right, of course.)
Next We Need Time
This is the place where a lot of younger GMs mess up. To be fair, a lot of more experienced GMs (including myself) mess this up as well. Relationships take time to develop. This becomes even more true when you are playing a game and know that what you are developing a relationship with is an NPC. Players tend to trust PCs over NPCs simply because the other PC is a dedicated and constant presence and it is a lot less likely to be part of a GM plot to snag them on something. To mitigate this you need time. Don't strike at the target too early. Let them be a safe place, a presence that can be trusted. Don't over play them. Let it be subtle but there and the player will come to like the thing more and more. If the player is asking about the NPC (or house, or whatever) on their own without prompting, or mentioning them when the context may not require it you've probably got them.
Finally, You Strike
Which means it is time to strike. Now this doesn't have to be a fatal course of action. Despite the title being to kill the darlings, when it comes to an NPC you don't need to kill it to have the impact. Just put the NPC in danger. If it is not an NPC but an item of some sort, put it in danger. Burn down the house, steal the magic sword, or spoil the PC's honor by framing them for murdering the king. Then what? Well, then you get to watch the drama unfold as the PC moves to recover what was taken from them.
A Cautionary Note
The hardest part about this technique is actually in not doing it. For the longest time I would set up NPC relationships with PCs and then either the NPC would die, or be a villain, or betray the PC. It got to the point where I expected it and my players expected it. It also was a problem because it killed the drama on some things. For this technique to work properly you CAN NOT do it every time or even that frequently. The PCs need to have relationships and things that are theirs that they can keep and feel safe with. They need the majority of those things to stay safe and kept. Otherwise they will be mentally prepared and thus resistant to the full impact of this technique. Basically, for this to work, you have to be very sparing in how you do it.