Toad85 said:
Also, in SPM, Bowser only joined Mario because he wanted to take the kingdom for himself, and couldn't if Bleck/Dimentio destroyed it. So no, he was never "good" in SPM, he just formed a temporary truce with the Mushroom Kingdom to fight off a common enemy.
Yes, I understand that, and he made clear this was still his only intention right before entering Castle Bleck. But my point is, why didn't he turn on Mario after they saved the worlds? I mean, once Smithy was defeated in Super Mario RPG, Bowser only didn't attack Mario because repairing his castle was his first priority, and as soon as he was all set to launch his attack in Super Mario 64, he did. But after Dimentio is defeated and The Void is closed, Bowser doesn't turn on Mario. You expect him to immediately return to his evil ways as he did in Bowser's Inside Story (although admittedly he didn't even technically join Mario in that game, he fought Fawful of his own accord and not knowing Mario was helping him)
Now, some may assume that upon return to the Mushroom Kingdom, he would gather his minions and get ready for his next attack (which could potentially be Galaxy or NSMBW). However, when Mario returns to Flipside from the Mushroom Kingdom, after what Merlon says is a long time, Bowser is still with them, and the fact that he remains with Mario, Peach, and Luigi so long after Bleck and Dimentio's threats (which are, after all, the only reason he joined Mario in the first place) are ended raises a few questions. If there was a turning point, my guess would be the fight with O'Chunks. I suppose the reasons for his near-sacrifice could be explained in that he might've thought he could be revived by his minions once the others saved the worlds, but then there was him trying to save O'Chunks from being crushed, arguing with him over who should go and who should hold the ceiling up...