Redemption Rejection/Playing With

Basic Trope: Evil character is offered a chance to Heel Face Turn, but refuses.

Straight: Magical Girl Hiroka offers Ryuko a chance to stop serving Queen Sangria and join her team. Ryuko laughs at the thought, telling her she's sticking with the winning side -- and anyway, she's never felt so alive...!
Exaggerated: Every time Hiroka or her companions face Ryuko, they beg her to stop serving the evil Queen before it's too late. She rejects them every single time.
Downplayed: Ryuko responds earnestly to Hiroka's offer of friendship, claiming that she'd happily accept if it were only so easy to cut loose from her dark past.
Justified: Ryuko sees no reason to turn against the Queen; after all, the only thing standing in their way are three pathetic little girls in silly dresses...!
Inverted: Ryuko starts reconsidering where her loyalties should lie; unfortunately, Hiroka isn't aware of this and kills her during their final battle.
- Ryuko tries to tempt Hiroka to the dark side. Hiroka emphatically refuses.
Subverted: When Hiroka offers her a Last Second Chance, Ryuko accepts.
Double Subverted: ...However, she only says that to get Hiroka to turn her back for a moment...
Parodied: Hiroka and Ryuko are two normal girls playing a ridiculously competitive tennis match against each other. Hiroka tries to "redeem" Ryuko by offering her a spot on her doubles team in an upcoming match; Ryuko, drunk on the prospect of victory, shoots down the offer and vows to destroy her arch-enemy here and now.
Deconstructed: Hiroka stops fighting so that she can belt out a rousing Heroic Speech to get Ryuko to see the light. Unfortunately, this is not a world where Talking Is a Free Action, and Hiroka just leaves herself wide open to attack. Ryuko doesn't even pretend to indulge her enemy, and wordlessly delivers a killing blow.
Reconstructed: ...But Hiroka's magic grows magnitudes stronger in the presence of malicious intent, and she effortlessly deflects the attack with a heretofore unseen power. By treating Hiroka's act of compassion as a chance for an easy kill, Ryuko has sealed her fate.
Zig Zagged: During her Dark Magical Girl phase, Budou rejected Hiroka's initial attempts to redeem her, first because she honestly believed the queen cared for her, then because she felt she didn't deserve any second chances. Ringo immediately jumped at the offer, but only because she was planning to serve as The Mole. But she quickly became the mask and turned on Sangria for real. In fact, Hiroka doesn't even want to redeem Ryuko, who she thinks crossed the Moral Event Horizon; she's only offering because she converted Budou and Ringo, and doesn't want them to feel like she didn't do all she could to help Ryuko...
Averted: Hiroka does not offer Ryuko any chance of redemption at all, nor does Ryuko plead for one.
Enforced: Ryuko has become a Draco in Leather Pants in the fandom, but the author doesn't feel she's redeemable. He only has Hiroka make the offer so that Ryuko can reject it, cementing herself as a villain who must be defeated.
Lampshaded: "Oh, stuff it Hiroka. I'm not interested in listening to another one of your long-winded speeches about how I should rethink my life and join your little band of heroes."
Invoked: Hiroka is a Nominal Hero who doesn't care about justice so much as having a good excuse to legally beat up troublemakers. But she knows it would look bad if she just opened fire on every villain she encounters, so she makes a show of pretending to offer redemption to her foes, intentionally making her proposals unattractive so that they inevitably refuse her 'mercy', thus giving her a good excuse to open a can of whoop-ass.
Exploited: Hiroka knows Ryuko's too haughty and overconfident and will reject the offer; she also knows that if Ryuko thinks she's trying to 'redeem' her, she's underestimate just how fiercely Hiroka will be fighting, and won't expect her to bust out her strongest magical attacks.
Defied: Ryuko realizes that rejecting the hero's offer for redemption often ends badly for the villain, so she decides to play nice and accept Hiroka's mercy... for now, at least.
Discussed:

Hiroka: "Oh wait, I think we're right around the point in the fight where I have to deliver the rousing speech that inspires you to repent."

Ryuko: "Ugh, do you have to? You know I'm just gonna say no, so why bother?"

Conversed: "You know, it's kind of refreshing that Hiroka wasn't able to talk down the villain of this arc. The fights are so much more interesting than the long-winded speeches, anyway."
Played For Laughs: Hiroka and Ryuko are exhausted of their magic, so the battle devolves into a slap-fight. Hiroka stops her 'assault' for a moment to ask Ryuko to give up and join the heroes. Ryuko responds by flicking Hiroka's nose and laughing.
Played For Drama: Hiroka and Ryuko are locked in battle, both seriously injured. As she charges her strongest spell, Hiroka calls out to Ryuko, offering her one final chance to turn back from this course. The other girl stops and considers, feeling her wounds... but then sneers at her foe's perceived weakness, taunting her. As if she's in any position to bargain--! But then light erupts around the magical girl, and Ryuko stares in horror at the approaching firestorm...

You fool! I am a Wikipedian to the last! Take your Last Second Chance and shove it back to Redemption Rejection, you Troper scum!