Drug dealers dont ask questions. They dont concern themselves if you drank a 40oz and injected heroin shortly before you bought their pill.
Oh I'm sure, but it sounds like fentanyl can kill you all by itself, unless I'm misunderstanding. And if that's the case, he might as well have given her cyanide.
If nothing else, a decent business man would at least let her know what she's taking, so she doesn't inadvertently deprive him of an income stream.
Dealers don't concern themselves with the quality control programs of their suppliers.
Dealers are middle men. Dealers are retail sales.
Dealers don't know and don't care if the drugs they are selling contain fentanyl.
The people making, producing the street drugs add fentanyl to their drugs because it is cheap and it gives their drug a kick that hooks the user. But the limited, if any, quality control in production practices don't always keep fatalities from occurring from time to time.
It isn't the dealer who is at fault, it is the people mixing the drugs in basement or shipping container somewhere.