Coincidentally, Mario in his first game (the original Donkey Kong) was depicted as a naughty carpenter who abused his own pet, Donkey Kong. In the prequel Game & Watch game, Donkey Kong Circus, Mario forces poor Donkey Kong to perform at the circus by juggling pineapples and dodging fireball, and even laughs at him whenever he either gets hit by a fireball or drops a pineapple.
His role just worsened in the sequel, Donkey Kong Jr. as he is actually the villain in that game.
Mario appears as the main antagonist in Donkey Kong Circus. Mario is an audience member who laughs at Donkey Kong, the new attraction of the circus, whenever he drops a pineapple or gets hit by fire. In the end of the game, Mario is shown in the construction site where the first game begins.
Donkey Kong Jr. (game)
Mario went on to imprison Donkey Kong in a cage. Donkey Kong Jr. went on to try and rescue his father. Mario attempted to stop the young ape and released various types of traps mainly consisting of animals. Junior eventually did make it to his father and the two returned to Donkey Kong Island just after Donkey Kong made a shot at Stanley the Bugman's greenhouse.
He also whipped the animals that worked for him, eventually known as Mario's slave labor. This makes him extremely evil and cruel, as he also let unnecessarily made them know who was in charge (him) his role was not better before as he abused DK before the events of Donkey Kong. Jr.
In the arcade ending, he falls down, gets up and tries to catch Donkey Kong and DK Jr. while swinging his whip, but gets kicked by DK and goes back, runs away. In the NES ending, he falls down and a halo exists over his head. He won't get up and tries to catch them.
Donkey Kong II
Since Donkey Kong II serves as a semi-sequel to Donkey Kong Jr., Mario reprises his role as the antagonist. Essentially, it contains the same story as Donkey Kong Jr.—Donkey Kong is trapped by the tricky Mario, and now the ape's son must save him.
Donkey Kong is chained to the floor in the top of the upper screen by several locks. Donkey Kong Jr. must hit a key up to the top screen and then progress through the bottom screen, jumping over Snapjaws and sparks much as Mario jumped over barrels in Donkey Kong. Every time Donkey Kong Jr. jumps over a Snapjaw or spark, he receives a point.