Hear me out when I say, Luigi is a surrogate mother for Jr, and all of the kids in general.
He just brings snacks when Mario and Bowser are fighting and then he just sits there with the children and eats the snacks and talks about their favorite dinosaur or something
He just chills out with the kids while Mario and Bowser beat each other's asses, until he finally just steps in and it goes like —
*Mario and Bowser, going at each other's throats*
Luigi: *sigh* Bowser! Mario!
*They stop and look at him*
Luigi: Bowser, put him down.
*He puts down Mario*
Luigi: *walks over to them* Now, it's been too long of a fight, so I'm gonna need you to stop. The kids are getting hungry and so am I. So, stop fighting.
Bowser: But-
Luigi: No. Buts. Stop fighting. Now.
The fight just ends, Mario goes over to Peaches castle and Luigi makes lunch for Bowser and the kids
