[quote="Flip_FTW"]Simba does seem more aggressive than Muffy, though...[/quote]
Oh, yes. That, I agree with.
In fact, it's almost like Mufasa is the tank, while Simba is the damage dealer.
But, I think Simba
had to be aggressive. It wasn't really his choice to rip Scar a new one; he was kinda forced into that situation, as a result of Scar's own aggressiveness. Simba had to try to appear bodacious, so that he could show the lionesses he was capable of overthrowing Scar, and so that Scar was less likely to fight back.
Mufasa was already the king. He didn't have anything to prove. All he had to do was just sit there and protect what he already had. Of course he wasn't going to appear to be very aggressive.
You can't really even compare the two. Mufasa was the guardian whereas Simba was the knight, if you catch my drift.