Aqua said:
I think he's trying to make a comparison between Luigi and Bowser's hypothetical brother, in that just like Luigi is submissive to Mario, the brother would be submissive to Bowser. At least that's how I understand it.
I've been prodded and coerced under threat of harm into checking this thread out, but honestly, I don't know if I can actually add anything. It's just a theory.
Considering Bowser's motivations, I would say he falls into chaotic neutral territory (I know he self-identifies as evil, but that seems to be just an image he wants to project. He doesn't really revel in destruction and pain). He does the things he does because he can. Because it's something he wants to do at that moment.
Like, I imagine sometimes he just has a slow evening, nothing's on TV, he's bored out of his mind, let's go kidnap Peach again, why not. It's been two days since the last time, that's long enough, right? Or he saw a commercial about cake, it looked good, he never really tried it, let's "ask" Peach to make a cake for him. He just does things because they're fun.
As for whether he cares for his son: I believe yes, he does. He doesn't really pass for an average dad, but he cares in his own weird way. He includes his son in his schemes, he gives him toys and various means of entertainment (most of which you'll have to fight), and he even lets him have a crack at fighting his arch nemesis. I'd imagine this to be the Bowser equivalent of a father playing football with his son. Family bonding over beating up Mario.
Plus, he's a king. He has subjects. If he needed a mother-figure for his son, he could easily hire a nanny. A role which, as was pointed out earlier, is already filled perfectly by Kamek.
And regarding the Bowser's brother thing: He could have one? There's no evidence that he has one, but the absence of evidence isn't confirmation? Though if he has one, they probably either aren't aware of each other, or they don't talk much.
Ok, I did it. Now please release the hostage.