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One is The Corrupter while the other is The Conscience. Right Way/Wrong Way Pair might be related
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Not exactly that... The two persuading characters don't have to be strictly good/evil, but they do have conflicting viewpoints. They might even both be protagonists. The important bit is that they're causing a moral dilemma for the third character, and it usually happens in a high-pressure situation.
I swear I've seen this trope before and I can think of a couple examples, but I'm not sure if it's here on TV Tropes.
You described Morton's Fork, but that's more about the choice than who is suggesting the choices.
ETA: On second thought, what you actually described is Sadistic Choice ("Keep the MacGuffin: villain kills you. Give his the MacGuffin; villain kills everybody else")
Edited by Freezer My name is Freezer and my anti-drug is porn.
Is there a trope for where two characters are trying to persuade a third character to do/not do something? E.g. "It's hopeless, just give the villain the MacGuffin already!" "Don't do it, you'll doom us all!"
A bit like Good Angel, Bad Angel, but with actual characters instead of miniature versions of a character.