An S-Block (also known as a reverse squiggly) is a tetromino who looks like an S. In most games it can only clear up to two lines at once. However, in some games that use SRS, he can clear up to three lines at once.
He is also the main antagonist in the game, even worse than Z. This is because it is inconvenient, especially when you are set up for a Tetris and you get this tetromino.
He is the twin brother of Z-Block and a masochist who has a crush on O-Block. He loves his sister and wishes she would go outside more or play Dungeons & Dragons with him. He plays a Half-Orc Paladin and loves to watch Young Sheldon