I would destroy them all, every last one of them.
I want the world to burn, want to see them suffer just like I suffered when they abandoned me.
I was adopted by the king and queen of the underground, the leaders of the monsters, but even with their kindness, I cannot forget, I cannot forgive. Not today, not ever.
I will bid my time, I will wait. Even in death, I am not gone. I linger, waiting, bidding my time until a worthy soul arrives and allows me to enact my revenge.
I will destroy this world until there is nothing left, and then I will move on to the next.
Humans will regret harming me the way they have, and as for monsters, they'll be finally free from their miserable lives underground.
Nothing will remain when I take my revenge on those horrid humans I am unfortunate enough to form a part of.
I will have my revenge, just you wait.
I see him. Frisk, that poor little boy who has fallen into the world of the monster. He will do. I just need to ensure he is corrupted enough to host my soul, and wait...
wait as I have waited until now. Soon, all shall fall.