I have two contradictory headcanons for Dr. Mario at this point and I like them both equally.
Headcanon #1 (nostalgic): Dr. Mario is Mario & Luigi’s dad. Yes this is largely out of blog nostalgia but also I still love it because reasons.
Headcanon #2 (canon compliant): Dr. Mario is Mario from a disease-ridden alternate universe and was forced to become a doctor because the Mushroom Kingdom (and Bowser’s Kingdom) is so desperate for doctors that they’re willing to recruit actual infants and the virus outbreak is so high that the only two choices for an individual is to either become a doctor or doctor’s assistant (often at such short notice that they’re unable to get a medical degree) or fall victim to the virus themselves.





