If a player suggests something to an NPC for reasons that would clearly only benefit the player's own character, try having the NPC inexplicably go along with it. The player will think they got lucky with a Fast Talk attempt or something, or the NPC is incredibly gullible. But if you do this, make sure the NPC has well-grounded motivations of their own that can be made to appear to line up with the PC's plan - but that in reality completely wreck whatever the PC had planned.
The cool thing about having secret NPC motivations is that the players will figure them out at different times. What will be a complete mystery to some will be obvious to others.
And it often works out in the least expected way.
Padmé: So, this is great! How can I help?
Anakin: There's one unknown factor. We need to find out who Gunray's sleeper agents are. I'm checking the Archi—
Padmé: You mean apart from Mace Windu?
Anakin: Muh... buh?
Padmé: I wonder who the others could be.
Anakin: Mace Windu?
Padmé: Sure. The clone army was funded from the Jedi Treasury.
Padmé: And we know the Jedi Archives were corrupted by "dogs" - that couldn't happen without someone on the Council letting them in.
Anakin: Oh my— That's why he's so vague all the time!
Padmé: He's so what?
R2-D2: Holy cow! And he never remembers his dreams!
Anakin: He doesn't even—
Anakin: Sorry my love, I have to go!
C-3PO: Ace reporter C-3PO for the Droid Daily!
C-3PO: Senator Amidala, any comments on friction in the Padmikin household? Innocent dinosaurs dying on Naboo? Your baby bump?