A few of my past choices:
Make them your eternal slave, signing away their soul in blood,
Remove a hand,
Remove a finger! Repeat as necessary, with as many characters as possible,
Make them swear on their mama that they won't come after you,
Send them packin' naked into town, then make their lives a living hell by making a hilariously cruel treasure-hunt for their lost loot,
Extract valuable information, which you can use to blackmail them,
Terrorize them for half an hour, so they'll understand perfectly who they're messing with,
Kidnap them and extract ransom from their friends/allies,
Take them to the Illithid for enthrallment,
Shoot a crossbow next to their feet repeatedly, screaming, "DANCE, GOBLIN, DANCE!"
Drag their ass through the streets of your favorite part of Sanctuary, screaming obscenities
Kill them, but return their corpse and belongings to their allies, ensuring they will be raised. This last one is very extreme, and I generally take it to mean "Back off. Back the fuck off." It's the last step before FD.
I thought about making a thread like this one myself, but I'll tell you why I didn't - people shouldn't have to look for a thread like this to come up these ideas. These should come as a natural progression of IC actions and their consequences. Of course, many players simply resort to FD'ing their enemies as soon as they can. But, what players should understand in my opinion, is that even in the FR, where death isn't necessarily permanent, killing someone is an extremely radical act, expressing the complete impossibility of any reconciliation/cooperation/coercion.
So, instead of suggesting actual 'ideas', here is my suggestion:
When you subdue an enemy of your character, have your character ask themselves this question: Why is this person my enemy? Why are they dangerous to my plans/goals/ideals?
When you come up the answer, you'll know what to do. If your enemy is dangerous because of their skill at arms, take away their sword, or maybe even their sword-hand, forcing them to live a life of shame and uselessness. If your enemy is a known political figure, who's tried to thwart your plans at every opportunity, extract secrets from them, then use them for blackmail and coercion. If your enemy is a bard who has been paid by an unknown party to slander your name, remove their tongue. If your enemy is the leader of a rival gang, burn their face so that they'll be so disfigured and horrible, no one will ever follow their orders again. If your enemy is a rival merchant, hold them hostage until his allies/retainers give you access to his bank account. The possibilities are as endless as the situations that may lead you to these encounters.
And in some cases, the character won't submit to any of these. If you try to blackmail them, they'll respond by being tough. If you try to torture them, they'll refuse to talk. If you kidnap them, they'll try to escape. If you cut their hand off, they'll hire a ganksquad to come gunning for you.
Is that a negative thing? Absolutely not. Meaningful roleplay, meaningful conflict and a meaningful rivalry have arisen from your decision to let them live.
Also, as a final rule of thumb: Always make sure the other player understands what's at stake. If someone comes to spy on your big bad evil meeting, insta-FD'ing them isn't cool. Kicking or chasing them out, explaining that the next time they go in, it's their death, THEN killing them when they return, is.
I hope this is good insight to players wondering what are the alternatives to FD killing someone else.
- K.