You can always see me in darkness, but never in the light. I make laughter lethal. But without me: your scars become a ride. You can find me in the soil, in the sea and in the sky.

The solution to this linguistic puzzle lies in a single letter that holds many roles within our language. Consider the first clue: you can always find this letter nestled within the word "darkness," yet it is conspicuously absent from "light." This initial hint guides us toward a specific character.

Moving on, this letter possesses the power to transform a joyous sound into something far more sinister. By adding it to "laughter," one arrives at "slaughter," a word with a decidedly deadly meaning. Conversely, its removal can change something painful into something pleasurable; take it away from "scars," and you are left with "car," a common mode of transportation. Finally, this versatile character is present in elements all around us, appearing in "soil," "sea," and "sky" alike.

This particular character is one of the most frequently used letters in the English alphabet, often serving as an indicator for plurals, possessives, and the third-person singular present tense of verbs. Its sound, which can be either voiceless, as heard in "snake," or voiced, like the 'z' sound in "is," makes it incredibly adaptable. Its distinctive serpentine shape is even thought to have influenced its ancient forms, making it a truly fascinating component of written communication.