Shadow is one of the most brutal Kaitou Joker characters. Blinded by hate, he wouldn’t think twice before killing off anyone that stands in his way. His spontaneousity as well as his unpredictability is what make him dangerous, and he’d rather blow everything up than using of actual strategy, which is his main difference with Joker. Although his hate and training to kill makes it worse, he had always had a short temper, even as a kid.
On the other hand, he’s very attentionate towards his little sister and would do anything to protect her. His devotion, whether it be for the good or evil, reverberates on his actions a lot.