Fullmetal.

Edward: Winry...
Winry: What?
...
Winry: Come on, just tell me straight!
...
Edward: IT'S EQUIVALENT EXCHANGE! I'LL GIVE YOU HALF MY LIFE, SO GIVE ME HALF OF YOURS!
Winry: You idiot... You want half of it? I'll give you all of it...
...
Winry: Wait, maybe not all, 90%! Wait that's still a lot... Maybe 80%, no 70%... Wait 70% is too little, maybe 85%...?

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Cutest confession and reaction I've read, I swear!
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A lesson without pain if meaningless.
That's because you cannot gain something without sacrificing something else in return.
But, once you've withstood the pain and overcome it.
You will gain a heart that's stronger than any other.
Yes, a Fullmetal heart.

-Edward Elric