Dante prefers to dress rather elegantly and fashionably while in the company of mortals and other creatures he considers beneath a demon's status, enjoying the panic and confusion in their eyes once they realize they are dealing with an otherworldly being. While in the company of other immortals and those he considers his peers, however, his attire is far more likely to accent his fearsome physique, displaying the many magical seals and symbols with which he's chosen to both augment and decorate his body.
On the surface it would seem that the depths of his knowledge are nearly impossible to calculate, having spent his youth traveling between the different realms of existence, and his time in the physical realm studying magics of all types. It would be safe to assume that his understanding of the universe far exceeds that of even the most learned mortal man.
Dante's childhood was one of both learning and suffering. Born of an angel mother and one of the fiercest demons, he felt outcast from the entirety of his family, neither completely welcome in darkness or light. To make matters worse, his father decided to complete his training in the hell dimensions from which the Blackflames originated. The creature that came back to Ayenee several years later was not quite what his father had anticipated, however, and instead Dante chose to go his own separate way rather than continue persuing Damaris' twisted goals. Now much older and far more wise, he's realized that being an outcast in a family full of them is far from the worse fate one could receive.
