"Undying Fidelity" was one of the last words/phrases told by Loki to his brother Thor in the Avengers: Infinity War movie in May 2018.

It was also used by Loki's fans and Tom Hiddleston stans to create a movement in Twitter to show the Russo Brothers their love for the said character.
I will forever cherish your undying fidelity for that man.

The hashtag, #UndyingFidelity, was used by some Twitter users to show their love for their favorite character.
by undyingfidelis August 3, 2018
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