Snow’s hair + Charming’s hair -> true love that can break any curse = the union of Charming and Snow (EMMA) is true love that can break THE curse. What do you think about eleanor89 theory ?

Now we know why Emma is the only one who can: it’s because Rumplestiltskin, the one who made the curse, put their hair in it so that the curse would be broken by their future son/daughter. It was in there from the first moment.

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