Since the game has been out for a while and there have been some questions on it recently, here's a guide to all of the endings in the game.

If you're not looking for outright spoilers: The game has two primary stats to manage, tracking how much Donny trusts you and how much Charlene trusts you. You'll need both Donny and Charlene to trust you to be able to achieve the best ending, and you'll need Donny to trust you to achieve a non-bad ending.

There are multiple ways to achieve each ending, so the following steps represent just one possible route through the game for each ending. Spoilers follow!

Common to best/bad/worst endings:

Remove her gag
Don't say anything
I'm Anakin
Can I get you some water or something?
I can't believe you let him announce his candidacy...
How do we show him that we're serious?
That... makes sense
You must care about him a lot
How do we get him to pay the ransom?
Look, I know you're a decoy
Maybe we should find a less-violent solution.
Why won't you pay us?
Look. I want to help. But you have to make it possible for me to help.
Tell the truth
I'm going to help you. Somehow.

Best ending:

Let me do it
Shoot Donny

Bad ending:

There has to be another way

Worst ending:

She's not his soulmate!

Normal Ending:

Don't do anything
He said not to say anything stupid
You deserved that
That's the plan
Shut up or I'll gag you again
You're not nearly as important as you think you are
How do we show him that we're serious?
That... makes sense
What's he like? Charlie?
Why wouldn't he cooperate? It's just money
You must mean a lot to him
Let me do it
You have to pay us
Look. I want to help. But you have to make it possible for me to help.
Once the money comes through, we're going to let you go
Let me do it
Shoot Donny