I think at one point dabi wanted to genuinely become a hero and had looked up to his father in a healthy way but over time especially when the con that came with his quirk came up he began to feel the obsession and once shoto was born he was anxious and so he tried attacking. Basically maybe hints of obsession mightve been there but it was definite once shoto was born
YAY ITS UPDATED, (he protec his chest hairs :] )