I think Vadic smokes for these possible reasons.
1: Vadic in episode 7 is shown to be 3 different things/people. 1a: Sadistic section 31 scientist, 1b: A changeling that was tortured by the scientist, and 1c: Some kind of evil being that has control over Vadic.
2: If you consider Vadic as above like I do, I feel both the section 31 scientist and the tortured changeling are being controlled and tortured by the floating evil head boss creature. The "boss" absusing the tortured changeling by changing it's shape and form looked painful and distressing to Vadic. In fact, after her orders and when Vadic sat down she shed a small tear from her eye and looked scared very badly. I think that tear came from the human scientist trying to fight the changeling. Same contrast as Data and Lore fighting each other for the body.
3: How this fits into the smoking? I think the smoking is the human scientist who had that bad habit before she was merged with the changeling. I don't think the changeling "copied" her. They are both in there. But the scientist is overpowered by the changeling, but in an effort to kill herself the scientist somehow makes Vadic smoke like a chimney as a way of fighting back or like I said - to try to hasten the death of the changeling.
1: Vadic in episode 7 is shown to be 3 different things/people. 1a: Sadistic section 31 scientist, 1b: A changeling that was tortured by the scientist, and 1c: Some kind of evil being that has control over Vadic.
2: If you consider Vadic as above like I do, I feel both the section 31 scientist and the tortured changeling are being controlled and tortured by the floating evil head boss creature. The "boss" absusing the tortured changeling by changing it's shape and form looked painful and distressing to Vadic. In fact, after her orders and when Vadic sat down she shed a small tear from her eye and looked scared very badly. I think that tear came from the human scientist trying to fight the changeling. Same contrast as Data and Lore fighting each other for the body.
3: How this fits into the smoking? I think the smoking is the human scientist who had that bad habit before she was merged with the changeling. I don't think the changeling "copied" her. They are both in there. But the scientist is overpowered by the changeling, but in an effort to kill herself the scientist somehow makes Vadic smoke like a chimney as a way of fighting back or like I said - to try to hasten the death of the changeling.