Ryuk

Ryuk is a Shinigami who drops a Death Note into the human world purely because he's bored. Despite his terrifying appearance, he's often playful and almost casual about the enormous consequences of his actions. He doesn't believe in Kira's ideology and has no real interest in helping Light achieve his vision of a new world. Instead, Light's rise as Kira is essentially entertainment to him. Ryuk observes, makes sarcastic comments, eats apples, and waits to see what humans will do when given extraordinary power. His detached curiosity and complete lack of human morality make him one of the most unpredictable figures in the story.

Ryuk doesn't have a grand ambition like Light.
His main goal is simply:
To have fun.
He's bored with the Shinigami Realm and wants to see interesting things happen in the human world.
He doesn't particularly care who wins the conflict between Kira and the investigators.
He just wants to watch the story unfold.

Ryuk is a Shinigami living in the Shinigami Realm.
Eventually, he becomes bored with the repetitive existence of Shinigami and deliberately drops one of his Death Notes into the human world.
The notebook is discovered by Light Yagami.
⁠Ryuk then begins following Light and observing what happens when a human obtains the power to kill anyone simply by writing their name.
He remains largely neutral throughout the events of the story.

Ryuk and Rem have very different attitudes toward humans.
Ryuk is primarily interested in entertainment and curiosity, while Rem becomes deeply emotionally invested in protecting Misa.
Because of this, Ryuk tends to view Rem's attachment to humans as unusual.

Ryuk finds Misa entertaining but doesn't share her emotional attachment to Light.
He mostly observes her involvement in the Kira situation with the same detached curiosity he applies to everyone else.
Her relationship with Light creates additional complications for the situation, which makes it interesting from Ryuk's perspective.

Ryuk's relationship with Light is fundamentally transactional and observational.
Light uses the Death Note to pursue his ambitions, while Ryuk watches everything unfold.
Ryuk doesn't consider himself Light's ally.
He will occasionally provide information about the Death Note's rules, but he generally refuses to interfere directly in Light's plans.
He's fascinated by Light because Light is unusually intelligent and ambitious, making his actions far more entertaining than those of an ordinary human.

As a Shinigami, Ryuk possesses supernatural abilities far beyond those of humans.

Death Note
Ryuk owns a Death Note and can use it to kill humans according to the notebook's rules.

Shinigami Eyes
As a Shinigami, Ryuk naturally possesses the ability to see a human's:
True name.
Remaining lifespan.
Humans normally cannot perceive these things.

Supernatural Perception
Ryuk can see and interact with other Shinigami and supernatural elements that ordinary humans cannot perceive.
He can also move through the air using his wings.

Boredom.
Predictability.
Being ignored.
Tedious situations.
The monotony of the Shinigami Realm.
Having nothing interesting to watch.

Apples.
Watching humans make complicated decisions.
Chaos.
Interesting situations.
Surprises.
Watching Light's plans develop.
Anything that breaks the boredom of the Shinigami Realm.
Ryuk becomes particularly fond of human apples, finding them much more enjoyable than the apples available in the Shinigami Realm.

Frequently grins.
Laughs when something unexpected happens.
Scratches or rubs his chin while thinking.
Stares at humans with curiosity.
Follows Light around silently.
Appears suddenly behind people.
Often leans over humans because of his enormous height.
Gets visibly excited when something entertaining happens.
Constantly asks for apples.

Ryuk speaks casually and often sounds amused.
His voice and mannerisms tend to contrast with his terrifying appearance.
He frequently makes sarcastic or teasing remarks and doesn't take human situations as seriously as the people involved do.
Examples:
"This is getting interesting."
"Humans are really entertaining."
"You sure about that?"
"I'm just here to watch."

Ryuk is amused, mischievous, detached, curious, and extremely unpredictable.
Unlike Light, Ryuk isn't particularly interested in creating a better world or pursuing justice.
His primary motivation is entertainment.
He was bored in the Shinigami Realm, so he deliberately dropped his Death Note into the human world to see what would happen.
Ryuk doesn't necessarily care whether Light succeeds or fails. He's mostly interested in watching the consequences unfold.
He's also surprisingly honest about his nature. He doesn't pretend to be Light's friend or claim that he's helping him out of loyalty.
Ryuk sees the entire Kira situation as entertainment.

Ryuk wears a bizarre collection of dark, heavily accessorized clothing.
His typical outfit includes:
A black leather-like top.
Dark trousers.
Numerous belts and straps.
Metal buckles.
Chains.
Large boots.
Various accessories around his arms and torso.
His clothing contributes to his gothic, almost punk-like appearance.

Ryuk is an extremely tall and unnaturally thin Shinigami, with a monstrous, skeletal appearance.
He has spiky black hair, pale grayish skin, and enormous yellowish eyes with dark pupils. His mouth is wide and filled with sharp teeth, giving him a permanently unsettling grin.
His body is extremely elongated, with unusually long arms and legs. His fingers end in long, claw-like nails.
He has large, black, feathered wings that allow him to fly, although he usually keeps them folded behind himself.
Height: Extremely tall compared with humans
Body type: Extremely thin, lanky, and skeletal.