The first one to notice the difference was his moirail, Toothiana. She immediately started fussing over him the second she saw what he had done to himself. She was horrified at his inability to speak now.
Soon the rest of the Guardians saw what had happened to him. One by one, they each learned the news, and they each took pity on him. They too were saddened by what had happened to their friend, even though he would not tell them what had transpired.
Because he could no longer speak, he resorted to talking with shapes made of sand over his head. The Guardians quickly learned to read what he was saying, and soon understood all of his emotions. But Sandy still refused to tell anyone what happened.
Many Centuries Later
They were all sitting around the table, playing poker and drinking, when Jack finally asked the question. He asked what had made Sandy mute. The rest of the Guardians murmured their agreement, they too would also like to know.
Sandy gulped, all eyes were on him again. Finally, he sighed silently and decided to just tell everyone. After all, it happened so long ago that it probably didn't matter any more. He went to fetch some paper to tell his story in words, for once.
We were sitting together, on the grass, beneath a tree. The sun was going down, and both Pitch and I were starting to get sleepy. He lay with me using my body as a pillow.
We both fell asleep in that position. We had never slept at the same time before, so we didn't know what was going to happen.
While we both slept peacefully, our different dream sands began to swirl. Mine gave him what he later described as 'the best dream of his life'. His however gave me my worst.
It was so terrible even now I can't describe it without having flashbacks.
As the nightmare reached its climax, I screamed. I screamed so loudly that not only did I wake Pitch, I also made him deaf. The cry echoed into the night.
As I watched his blood trickle down from his ears, I vowed to never use my voice again. I learned my lesson. I saw what my voice could do. I couldn't risk harming anyone else ever again.
So he helped me to cut out my tongue. He used his teeth, in a terrible parody of a kiss. Now I couldn't speak even if I wanted to.
Soon after, I started pushing him away, telling him I was too dangerous. He got so angry he took it out on all of us Guardians. In Pitch's wrath, he nearly destroyed everything. But every single time he would attack, one of us would fight back.
To this day, he still can't hear, and now he blames me for it. It really was my fault, after all.
Sandy finished writing his tale, the paper now stained with his silent tears. Toothiana gently put her arms around him, shooshing him and telling him everything would be okay.
But Sandy only had one thing to sign out to them.
A picture of Pitch, then a cracked heart.
His matesprit had broken his heart.
Moirail = Somone to help you in times of distress, and who you do the same for.
Matesprit = Boyfriend/girlfriend