What? Who are they?
Well… I’ll start at the beginning. Brandon Sanderson is a good high fantasy author whom writes of very fantastical worlds each with odd rules magic that avoid “It’s magic I ain’t gotta explain shit.” If you are a fan of that, I suggest you start with Elantris, Warbreaker, or the Mistborn trilogy of his. I’ll wait!
These are characters from the Stormlight Archive which takes place in a world that has gravity magic, transmutation magic, magical swords that can cut people in the soul, magical suits of armor that act like power armor, gemstones which capture magical essence that power all the former, an ecosystem where plants can hide in stone and animals are mostly crustaceans because hurricanes blow across the continent like every week or so, and giant enemy crab monsters.
Kaladin is a surgeon turned soldier whom survives things alone that he wishes he hadn’t and is thus gloomy about it and Syl is an odd spren (spirit elemental…thing) that follows him around and is weirdly sentient.