A long time ago, a single mushroom was growing in a forest. A purple mushroom, with green spots, and a very bone-like material as the stalk. Years later, a skeleton rose from the ground in that spot, his skull topped by the head of a mushroom, and his soul free. He began to roam the world, eventually finding a human settlement where he attempted interaction, and was hastily rejected due to his appearance being frightful. Saddened and discouraged, the skeleton roamed more, stumbling across a demon settlement, where they welcomed him as a brother. There he learned how to live for himself and how to care and defend people he loved.
Eventually the demons were enraged at the humans, who slaughtered the livestock and burned down a forest. When the skeleton heard the demons were going to go and pillage the humans, the skeleton was glad to join in the endeavor, and marched onwards to go and kill the humans who insulted him so long ago. Once they were there, the demons slew all of the men in the settlement, leaving only the women and children captured.

As the demons rejoiced in their victory, the skeleton couldn't help but feel remorse for what he did that day, how he killed those men, and what the demons were going to do to the women and children... Right before the unforgivable happened to those captured, the skeleton drew his sword in the name of justice, and defended the humans with all of his might. The amount of blood spilled that day was unforgettable and traumatic.

From that day on, the skeleton took an oath to himself. He would defend mankind with his life, until either the day he died for good, or the day that mankind betrayed him.