Abuse as a Generational Cycle
In the same way that Ian's abuse to Kirsty and Tim over the years has led them to abuse themselves -- emotional rejection and excessive underage drinking, -- Dylan's father's rejection of his family has led him to reject the sanctity of life. The message from both of these fathers to their children is that these kids are not valuable or acceptable. Because this is the dominant message being communicated to them from a person whom they should be able to trust implicitly, the children all in some way come to believe what they're told and to perpetuate the abuse, mostly to themselves. There is a kind of addiction to abuse, which forms a cycle difficult to break. In Dylan's case, his father left him feeling utterly worthless, so he decided another abusive father must be equally worthless for treating his family like he does. Although these responses by Kirsty, Tim, and Dylan are the result of trauma, they are not necessary responses. With proper outside support to build self-respect and to speak against these abusive messages, the kids would be able to work through the trauma in healthy, constructive ways instead of furthering the abuse.
Devaluation of Life
Because his father abandoned the family, Dylan feels utterly worthless. He comes to believe that his own life doesn't matter, but he demonstrates this through the incident with the possum as well as his plans for Ian. In order to prove to Tim that he can kill, Dylan tries to persuade him to kill the possum, but Tim refuses. Although Dylan asks advice from his Grandpa, he takes license in the response as if he'd directly asked, "Is it ok to murder?" He kills the possum in cold blood and then prepares to do the same with Ian. Both of these incidents demonstrate an alarming trend in Dylan's psychology which indicates that he does not consider life precious, which naturally extends to even his own life, where the thought process began.
Isolation
The abuse in the Beale household persists because the family is isolated. As kids, Kirsty and Tim don't possess any knowledge or power to confront their step-dad. Even more, they are living in a precariously dangerous situation because Ian could seriously harm them if he decided. Because the mother is suffering from her own mental health troubles, she is further isolated from adult company. Ian has told his brother on the police force that she is crazy and making up lies. Since there's no proof to the contrary, this inside story gains credibility. Without an ally in the authorities or anyone with the mental or physical capacity to stop Ian, the sheer isolation of the family opens up to this kind of exploitation. If surrounded by a loving, supporting community, things may have panned out differently for the Beales.
