One

Metanoia: The journey of changing one's mind, heart, self, or way of life. (N.)
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Natsu Dragneel is mates with Gray fullbuster.
Only there's one problem.
Gray wants to kill Natsu.
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Natsu hasn't changed as a person, so can he make Gray see that? Or will gray make Natsu hate him?

As they say, no one can hate you more than someone who used to love you.