So we have a "good Noxian" in Riven. But why is there no "evil Demacian"?
ITT: Lucian doesn't count. He still fights the good fight. And Fiora's not evil, just snobby.
Why is there no Demacian who exploits the legal system for his/her own gains, or manipulates politics for selfish reasons? Too hard to write?
EDIT: For Vayne, she SOMEWHAT qualifies, but IMO she could be written as a non-Demacian and it wouldn't entirely matter.
EDIT: Here's how I'd do it (roughly). (I'm using the name Nephree to represent the Champion in question.)
Nephree is a member of Demacia's Justicars, who are kinda like detectives/police/royal guards/etc. At one point in her career, Nephree becomes witness to a murder, but the killer is a highly-respected noble, who uses a spell to confuse her and then pins the murder on her. Due to the noble's meticulousness, all the evidence points to her, and her word that she is being framed is met with disbelief by the city guards. She is forced to run, evading capture.
While hiding, Nephree desperately tries to think of a way to prove her innocence. At this time, she is approached by Aatrox, who offers her a Darkin sword as a way to give her the power she needs to bring the murderer to justice. Desperate, she accepts, but becomes cursed by the sword.
Nephree returns to Demacia and confronts the nobleman, defeating his guards and arresting him. As Jarvan IV arrives (the two are old friends), Nephree is able to make the nobleman confess to the murder and to framing her. But then, before she can hand the noble over to Jarvan to be imprisoned, the sword's curse makes Nephree lose control and she kills the noble.
Nephree is not charged for murder because Jarvan knows that the sword made her do it, and she could not resist. However, due to the curse, Nephree cannot compel herself to get rid of the sword, nor can she or anyone else in Demacia destroy it. Nephree now seeks to find Aatrox again to get the Darkin Blade to free her of the curse, one way or another.
NOTE! The whole "pin the murder on her" thing isn't impossible. Hard, but not impossible.
Funny thing with Riven is that she's essentially a lot like Darius. Both hold the old Noxian ideals in very high regard and both want to 'fix' Noxus to be more in line with it. The difference is that Riven is, ultimately, weak-willed while Darius is not. Riven abandoned the system rather than trying to save it (while claiming she wants to) while Darius is willing to lead by example and fight the corruption on its home turf. When he sees his leaders doing something that disgusts him or pisses him off (wasting troops, for instance) he doesn't mope over it, he deals with them in the standard Noxian fashion, by killing them.
Vayne is an enemy of black magic and doesn't really care where it comes from or what it's being used for. The only reason she doesn't come across as a fanatical zealot is because most users of black magic are, indeed, evil. I have no doubt, however, that she'd freely kill even morally-ambiguous cases like Annie or Ahri and would probably even take shots at the definitely-Good Kassadin. The only reason Vayne is still classed as a 'good guy' is because she hasn't gone after those champions in lore yet, and she has a lot of more blatantly evil targets to go through first.
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