Artemis Fowl II is a child prodigy who is originally an adversary but eventually an ally of the fairy civilization. He has Irish ancestors, black hair, blue eyes, very pale skin, a nearly dysfunctional familywith an elaborate history of crime, a loyal manservant and bodyguard called Butler, millions of euros at his disposal, and the highest intelligence of his generation. He is also a criminally good genius who thinks of ingenious yet wicked schemes in order to restore his family's fortune.
Artemis has the "highest tested IQ in Europe". In the beginning of the series he regards everyone as his inferiors, as his latest school counselor, Dr. Po, has correctly concluded. He trusts no one completely, not even his parents. He however places trust on his bodyguard and later on Holly. Though he is quite distant to his parents, Artemis loves them and cares for their welfare, as shown when he relinquished half of the ransom fee he received in Artemis Fowl (book) in the hopes of curing his mother's insanity.
Initially, Artemis seems to possess a cold, ruthless, almostpsychopathic nature. He rarely laughs or cracks jokes. He is shown to have daily pessimism in the first book. A smug, sarcastic and extremely intelligent criminal mastermind, it is shown that though sometimes he also regrets and detests his own schemes, he passed it as necessary for the sake of his father's life. However, as the series progresses, influences from his family and the fairies have him showing the more compassionate side of himself. Artemis forms friendships and becomes much more selfless, doing things for others without demanding payback. As Holly has noted, he has also developed a sense of humor. He also cares about his mother, as she suffers from depression, strange phobias etc.
In The Time Paradox, during his procession to the past with Holly Short, he seems to have begun showing signs of puberty, and seems slightly more aware of his female counterpart. Also during The Time Paradox, Artemis takes note of and is appalled by how antagonistic he was at a younger age, and how sadistic he once was toward certain others, one namely being Dr. Kronski.
Artemis is sometimes shown as lonely and miserable. Though he states in the first book that the only medical problem he has is a slight dust mite allergy, he has been known to edit out events and traits which he does not like (namely, a gasp of fear when exiting a train in The Arctic Incident) from his memory. Despite this, he is an expert in psychology and sociology.