Letterverse

Prologue

He woke up in a blank white space, alone, confused, and just- felt like he forgot something. Something that he was supposed to know, but didn't.

... where was he, again? Huh? Why was he here? Who was he? And how come he can't remember anything?! As a stream of questions started to flood his mind, he began to twist himself to look around him, desperately looking for something, anything that would give him some answers.

But all that hit his sight was white, white, and more white. Not even his body was an exception to this rule. At this point, the white was starting to become glaringly bright, but he persevered through it and kept on looking for answers.

Sighing quietly to himself, he let his vision swim around in the white one more time before finally looking downward, finally noticing a deviation from the white- what was it, again? Letters? Yes, letters.

Beautifully colored envelopes, to be exact, sitting next to his legs while neatly stacked together and kept together by a secure, blue ribbon. Something about the letters seemed to unnerve him, but he shrugged it off, the desire to recover his memories vastly overpowering his suspicion and skepticism on how and why there were letters around him.

As he crudely tore off the ribbon away from the letters, he quickly took the first envelope in his sight- a baby blue envelope with a white hammer with some stars in place of a stamp, and the words Underswap Sans (Blue) scribbled on the bottom right-hand corner. Did he know this person-? Monster-?

His head hurt trying to remember.

Peeling open the envelope's fold, he started to read the letter's contents, hoping for any indications of answers to the questions that plagued his mind. And to hopefully find out what the heck he was doing in this place.