In the Galaxy Movie, Bowser Jr recounts his dad telling him “Nothing is more dangerous than a friend! They wait until your armor is down and stab you in the back!”
That had me wondering who betrayed Bowser in the past to get that mindset in him and make him teach it to his son?
Was it another big bad Mario villain who betrayed him, like maybe King Boo or Petey Piranha?
Did Bowser ever team up with another villain in one of the Mario games? (I haven’t seen it in any of the Mario games I’ve played.)
Or maybe was it not a villain, and it happened when Bowser was more good or neutral once?
Or maybe something Bowser’s father/father figure taught him and he continued on? He didn’t seem to remember saying that until Jr reminded him, but he didn’t seem to have a problem going back to rejecting friends after Jr reminded him, so who knows?