The thing that terrifies me about Jack is the fact, that - up to a certain point - he did nothing so much bad.
(And then he did everything bad, as we know.)
He lost his will to life in an early age, and unlike some other characters he had literally nothing and nobody to count on. Lacie was his only hope and will to breathe and Jack did nothing else than she advised to him:
To be with Lacie, he had to find her. And therefore, he searched for many years just to be by her side again.
The most frightening is that he did only what was necessary for his own survival. He wasn’t doing all these things for money or power. He even never wanted Lacie to “be just his” or something alike. He just wanted to live and be with her, because she was the only thing that made him feel alive.
Our green-eyed villain did everything in order to live, but he lost his own existence. When he lost his own existence, he began to both hate and love his will to life (yeah, Lacie). Jack started to hate Lacie, because on his way to be with her, he lost himself, but he also loved her, because she gave him totally lively feelings. Thanks to her, he known who he is and that he still lives. Jack Vessalius was empty and Lacie Baskerville filled him - he was too much addicted to her (that isn’t a healthy relationship, but he still wasn’t completelly “evil” trash - just manipulative trash when he used people around him to get to Lacie), and when he lost her, he went completely mad. And then, only then he commited the most unforgivable crimes.
But excuse my long speech. What I want to say is that…
There is nothing more terrifying than doing everything (or most of things) right and ending up in despair.
Something really dark and/or empty creeps into your head, you are unable to name it, but it destroys your whole life and your own self. It can come at any time and not everytime you can notice it. And when you do, you can’t make it stop. The fact that human madness can escalate into still worse and worse proportions and that at the end you can’t even say what is “good” or “bad” because you can hardly even notice your own existence, is… Okay, like I said hundred times - I see it as something really sad.
It destroys me to think that the human soul can end up so devastated and you don’t always have the strenght to stop it.
I’m not saying that Jack did everything right. No, he didn’t, even before Lacie’s trip to the Abyss. I’m saying that he tried, he really tried to make things in his life right, but he ended up like reflection in the water that’s just faking emotions for people around him and that he had just only thing to show him that there is still something under that mask.
Jack has done sh*tty unforgivable crimes and I just feel really sorry that he couldn’t find anything that could’ve stopped him. And actually, I feel sorry for anyone who is in similar situation like him.