You may spend the whole Unholy Mecha sequence laughing at constant radio banter between Rayne and Germans piloting other mechas. They're acting less like mortal enemies locked in a fight to the death and more like a bunch of teenagers wisecracking to each other during a match in an internet cafe.
When you begin to fire at them, it takes them quite a looong time to realize that one of their vehicles got hijacked. For about a half minute, they keep politely asking Rayne to check what she's firing at... until one of them snaps:
Mecha pilot: What am I saying!? Unit three, hold your fire!
To their credit, they at least remain Defiant to the End. After you've destroyed two hostile mechas, the pilot of the last one does not lose any of his spunk.
Mecha pilot: You know, I have had just about enough of you!
The battle against Krieger twins is quite funny as well, given the fact that Sigmund and Simon seem more interested in flirting with Rayne, rather than actually fighting her.
And after Rayne realizes that the twins' bizarre biology make one of them suffer from damage dealt to another, her reaction is to quip "so... you punch yourself when you're mad at your brother?". Simon bursts into laughter in response.
Rayne's reaction when Mynce — who was killed a second time during their earlier encounter — turns up quite alive and well again.
Rayne: You know, your whole coming-back-from-the-dead act is really starting to get old, Mynce.
After destroying Beliar once and for all, Rayne simply flips off his heart. She does the same thing to Wulf's dismembered corpse after cutting him into pieces.
The second game:
Zerenski's guests are mesmerized by Rayne's dress. One guy in particular:
That's definitely stimulating my economy!
Most of the game's humor comes from Rayne's snark. A few gems that come to mind:
Minion: The master — I mean, Mr. Zerenski — would prefer that all the guests remain downstairs, madam. Rayne: The master can blow me, monkey suit.
(after dismembering an enemy) And I thought somebody was going to lose an eye. (a car crash causes the bar to catch fire) I'm trapped in a burning honky-tonk and the jukebox is downstairs! Somebody's gonna pay for this!
There's a particular Squick-tastic moment where Rayne blows open Slezz's stomach and has to climb inside to rip out her heart. Amidst Severin's praises of her, and is seemingly traumatized by getting "bowel in her hair". She then climbs up Slezz's corpse to the exit.
Rayne: I think I need a minute alone ...
Rayne's first encounter with the Shadow Legion.
Shadow Legion Vampire: *whispering vampirish* Rayne: God, you guys and your stupid, secret dead languages. Always showing off.
And then there's the one she has later.
Rayne: Do you think it's cool? Really? It's not that cool. You're probably making it up as you go.
The minions have more than a few particularly funny moments.
We're getting our asses handed to us here! Drop the exit now! (the exit drops, crushing another minion into Ludicrous Gibs) Alright men, turn the pumps back on! LET IT FLOOOOOW!