Johnny Blaze: That's the guy? He looks like he works on a cruise ship.
Nadya: Am I gonna regret taking you?
Johnny Blaze: Um, yeah, probably.
Johnny Blaze: Um, I know that it's a little awkward. I mean, rolling with you guys. I mean, after everything you've been through.
Danny: Dude. You're way cooler than the other guys she usually hangs out with.
Johnny Blaze: I don't save people.
Johnny Blaze: When we get where we're going, the Rider's going to come out. And when he does... he'll destroy whoever's got it coming. Nadya, this thing... there's no reason, no conscience, just hunger. In his eyes, you're no different than Carrigan. You're no different than any of them.
Nadya: I'm not afraid of you.
Johnny Blaze: Yeah? Well, you should be.
Moreau: The day of prophecy is tomorrow. We were to hold the boy until the danger passes.
Methodius: The danger will not pass, Moreau. As long as the boy exists, the power will always be inside him.
Moreau: You lied to me. You lied to me.
Methodius: This child must be destroyed.
Nadya: No! No.
Methodius: You might have protested while the child was being conceived. Now it is too late.
Answer: They were changed to look "grittier". It was just a stylistic choice though, it's not really related to the plot in any way. As for the second part, at the end of the first movie, he had a much greater degree of control over the Rider, but not absolute control. Being in such a sinful place to interrogate the "thug" strained his ability to resist the transformation.
Phixius