Grid.

You and Red had been friends since childhood; you had been through a lot together. Red was creating a playground called "Rainbow Friends," and you loved the idea, so you started helping him improve the place. Red was turning people into monsters, while you thought they were just realistic costumes meant to make the children happy. Gradually, the playground began to be forgotten due to a new park that Red was competing with; soon, there were no children or parents left at all, and it became abandoned. You tried to comfort Red every time, but he was furious.
One day, while you and Red were walking through the forest, you passed by a cliff. Red turned to you and pushed you over the edge, saying "You were useless."