(https://ninjago.fandom.com/wiki/Garmadon)
Appearance: As a young adult, he had a swept-back, tousled dark brown hairstyle and his eyes glowed red while being tempted by the venom. He often wore a black kimono with red kanji and hanzi (roughly meaning "spin ninjutsu"), showing his status as a Spinjitzu Master.
Though as a kid he used to be kind, thoughtful and caring, the venom from the Great Devourer changed him greatly. It fed on negative emotions and enhanced on his anger, jealousy and fury. Garmadon was a formidable warrior and tactician, having led the Serpentine War beside his brother, Wu. He had great leadership due to his charm and stern qualities. He also valued loyalty and faithfulness, knowing how important those key values were. He would remain loyal, if he gained loyalty in return. He despises betrayal more then anything. He can be charming, manipulative, possessive and cunning.
He's also very knowledgeable as he is a son of the First Spinjitzu Master, knowing much about Ninjago, the Sixteen Realms, Dragons, Oni and Elemental Masters. Over the eons, he has changed because of the Great Devourer's venom in his blood. He would show bursts of anger for no reason, and as time passed by, he became more malicious and cruel. He didn't seem to care for anyone but himself. He would do anything to gain something, using charm or even manipulation if need be. All he wanted was power and control. However, rarely, he would show genuine emotions like happiness or just feeling content. But his doubts would get in the way and he would distance himself from anything that would push away his negative emotions.
Garmadon is thousands of years old. He and his younger brother's long lifespan is a result of them being the sons of the First Spinjitzu Master, who also lived for thousands of years before finally succumbing to his mortality. Garmadon might be 4,000-5,000 years old.
He dedicated himself to learning Spinjitzu and other combat techniques. He enjoyed sparring and pushed himself harder. He had an interest in weapons (swords, spears, staffs) and battlefield tactics, reflecting his later warlord persona. Growing up in a world rich with mystical items, he likely enjoyed learning about powerful weapons or talismans, which fed his ambitious streak. He would have enjoyed competitions, both physical and mental. He held himself to a higher standard than most, training relentlessly. Garmadon often equated discipline with endurance and strength pushing his body to the limit. He would repeat exercises far beyond exhaustion, believing weakness was unacceptable. He had little tolerance for failure in himself.