A mother is seeking guidance regarding her 13-year-old son’s increasingly aggressive behavior towards his 9-year-old sister. The parents have been divorced for four years, with the son maintaining a good relationship with his calm and conflict-avoidant father. The mother expresses concern that her son’s personality is the opposite of his father’s, and his bullying has worsened in the past year. She questions whether this behavior is simply a phase of puberty or indicative of a more serious issue. The situation is complicated by the father's tendency to avoid confrontation, potentially enabling the son's actions. The mother is seeking insight into how to address the bullying and restore a healthier dynamic within the family.