Here's a little trick I've picked up over the years that's served me well.
Players who come from a traditional background in roleplaying games, which includes the vast majority of us who came up playing stuff like D&D, are conditioned to think of NPCs as the enemy. In trad games, they're usually the bad guys if they're developed in any detail (I've seen players perk up when I delivered some details about a particular NPC, muttering "Aha. Must be the bad guy.") and even those without overt hostile intentions might constitute an obstacle of some kind. There's the vendor who's trying to screw them over on the price of a sword, the wizard who will only agree to help them if they do a little somethin-somethin for him first, the local sheriff just waiting to pounce on them if they commit a crime, and worst of all, the relative or lover who's used as a plot hammer when they get kidnapped.
This is why trad players don't like NPCs, and prefer to run characters with no ties to their community and no one they care about. A whole generation of player characters were bold, indifferent orphans predisposed to torch any towns who got in their way, because who needs the grief really? Safer to be a chaotic neutral bastard and be done with it.
As I've said recently, this kind of player character is dull as dogshit. If they don't care about anything or anyone, why would we care about them? How are they heroes? How are they even characters if they don't interact with their world and aren't affected by anything?
High Trust High Drama games tend to be populated by at least a few characters who are close to the player characters and unabashedly their friends. It's true, thankfully, that you don't need to kidnap an NPC to get the players to involve themselves in their lives as long as they feel a connection with that character to begin with. You can only ever threaten or kidnap a character once, but someone you care about can make emotional demands on a regular basis that require attention if you want that relationship to continue and grow. Making the relationship an asset, a pleasurable part of playing the PC (like a favourite magic sword), is the perfect way to turn the trad attitude around.
So here's the trick.
Often, player characters are surrounded by all kinds of antagonists. It's a very useful thing to be able to turn a character who they initially perceive as an antagonist into an ally. In my SHADOWRUN DISAVOWED game, one of the PCs had an ex-husband who she assumed might be complicit in "burning" her connections with the corporation. It turned out that he was actually on her side, and had been fighting to protect her from inside the company for some time. He was still an asshole that she could be glad she wasn't married to any more, but it turned out he wasn't a straight-up bad guy at all.
Players like to be surprised, and although surprises can be overrated, one of the nicest kinds of surprises in a game is discovering there's more depth to a character than you expected. Finding out that a character is actually on your side despite some differences, making you reassess your character's perception of the situation, makes both characters more real and textured. Protagonists often get to feel like they're the most righteous and "correct" in their worldviews, so affecting a shift in that perspective gives the character a more satisfying fullness.
In my swinging 60's London game, CARNABY STREET, one of the characters had set himself up as the black sheep of a well-to-do titled family, with a father who always gave him a hard time about his lifestyle. I managed to pull the carpet out from under him by revealing that the father would never consider ratting him out to the authorities, despite their bad blood, because at the end of the day they were still father and son. He was willing to go underground and cut all of his comfortable government ties to protect him. I think this was a startling (and, I hope, satisfying) development that let the PC know how loved he was.
Let me qualify this by saying that I'm a big believer in straightforward villains. A lot of GMs make the mistake of thinking that players want their villains to have realistic and complex motivations, but in my experience that's entirely overrated. Most of my players over the decades have best enjoyed the villains that were purely there to be hated and defeated, full stop. Explaining their deep background is often just navel-gazing for the GM, a different kind of Mary Sue character -- "Darth Sue", if you like. See how interesting and complex she is? No, that kind of complexity should usually be reserved for the player characters.
But that doesn't mean you can't surprise and delight them with little twists like this. It's a good trick; try it!