This started when my son (3 years) found my Mega Man art book and liked the robots inside. He asked me, "I want to watch this movie." I told him, "Sorry, all I have are the Mega Man games." "Let's play them!" he replied.
So, I showed him Rockman 2, and he really liked some of the levels. Now we play Rockman/Mega Man a couple of times a week: him choosing the robot, and me playing through the level. Fun stuff. He knows all of the MM2 bosses' names by heart, and most of the MM1 and 3 bosses too.
Even when he's playing with Lego or toys in the living room, he makes up new robot names, like "Globe Man" and "Apple Man", then he sings the boss intro theme from MM2. It warms my heart that the first game he has really started going crazy about (I gave him sheets with MM bosses on paper so he could colour them with crayons!) is also my favourite.
Here we are on our way to finishing Rockman 2:
(He's holding the Neo-Geo controller because we sometimes play League Bowling on the Neo together as well.)