Despite the Earl's evil intentions for the destruction of humanity and constant trickery into creating Akuma, the Earl always seems to act as a cheerful and carefree character. Allen Walker notes that the Earl always acts like he is playing the fool and a huge grin seems to be permanently fixed upon the Millennium Earl's face, with a speech pattern unfitting for the ultimate evil in that he always speaks in a cute, loving manner and ends his sentences with a heart. The Earl has also shown to be rather eccentric, an example is out of nowhere pulling out a rooster costume when trying to wake up Alma Karma. However their is more to the Earl's character than simply a fool trying to end humanity. He has shown concern and happiness in his actions for The Noah, and even anger after the destruction of the Ark, although whether it was because of his reminder of the 14th, or because he destroyed the original home of humanity, is unknown. The Earl seems to care for his fellow Noah a great deal and seems to be particulary close to Road even aiding her in her homework. Though he was a bit insulted when Tyki Mikk commented on his weight.
After learning that the original Ark was put into human hands, and that eighty-percent of the Akuma egg was lost, The Earl showed an incredible amount of anger.
After learning that Allen Walker was the reincarnation of Nea Walker the 14th Noah the Earl has asked him to join the Noah Family despite Nea attempting to kill 35 years prior and Allen Walker being an Exorcist, showing a forgiving side, yet at the same time he seems to hold a deep and intense hatred towards Mana Walker and refuses to ever forgive him showing that there is a limit to his forgiveness.
However, when confronting Allen during his run from Apocryphos, the Earl showed an insane and very deranged side saying Nea's name constantly asking him why he doesn't recognize him all the while his face changing more insane and crazier. He than remembers Mana suddenly and constantly chants his name in a deranged maner blaiming an intense event on him.
The Earl has shown a deep hatred for both Innocence and Humanity (to the point where he states that since the Ark fell into human hands, it was no longer worthy of being a Noah possession). Despite this he does have a somewhat soft spot for humans (or at least children) as seen when he buys flowers for a little girl and lets Allen live when he fails to turn him into an Akuma, though he did question his actions in the latter and this does not stop him from turning any human into an Akuma. His favorite food is crocodile.