I can kinda understand Law's twisted mind, after all he feels he has been used and abandoned by everyone. His parents used him and then died, even Jesse toyed with him and left him. All of these during his teen ages, which cause a lot of angst and insecurity. He feels that he doesn't have a person to rely on. And then come with a more twisted plan to get over all of it.
At the end, even if he was able to let go of the real Jesse, he wasn't even able to discard his feelings for him, becoming addicted to that pathetic machine.
Since the dog was with grandpa on a walk when the initial incident happened. But well, it's a dog. Probably isn't even aware what its capable of ╮( ̄▽ ̄)╭
He estado preguntandome lo mismo...
Me muero de la envidia si le salen cohetes por la espalda!... Quiero un perro así...
loool!!! Yo no!!!! XD Suficiente tengo con las mias XD