Well... Let's be honest, it's difficult for even die-hard Noxian lovers have always found it a bit hard defending Noxus. It's hard to fight against the fact that Noxus did participate in a rather imperialistic crusade against nearly everyone, but Zaun and Bildgewater. Then there is the minotaur incident. The barbarian pacification campaigns. The invasion and subsequent occupation of Ionia.
Domestically, you have a culture that condones murder as politics, enjoys death spectacles, has a nasty case xenophobia against yordles and Annie's people, a capital that contains some of the most dangerous slums on Runeterra, and actively practices necromancy. Not to mention, the leader for the last hundred years was a man who's last name was Darkwill. That's a name you run away from. This was all even before the lore slowdown. It's hard to find much "grey" with Noxus.
That said, I also want to say that we still don't know how Swain will shape Noxus. He and his partner in crime LeBlanc are wild cards to say the least. We've been given very little information on how things were when the Black Rose was in charge. For we know, things might have been significantly less militaristic, perhaps even harmonious to an extent. Darkwill obviously ruffled a few feathers in his rise to power, and he spent a very long time shaping Noxus into the country it is today. There's no doubt it's currently bent towards evil, but that might change in the future. I hope it does change a bit, as it would be interesting to see what might happen if Darkwill Loyalists clash with Swain's new leadership.
Then there is also Darius in the picture... For as much as people hate him, and as much as I griped on him early on, Darius is probably Noxus' only real hope for stability. He's described as a fighter of corruption inside the city, so perhaps the notorious slums of Noxus might receive some heavy handed love. Being a product of such a hell-hole, I doubt Darius would adverse to seeing the conditions of the poor improved. With this in mind, Noxus may start to grow a few gray hairs.
Also, because this seems to be a hot topic... I agree with Lithillya's sentiments on Syndra. As evil as she is made out to be, her elders can share a bit of the blame. They were truly callous about their actions. When it was discovered that Syndra's potential far exceeded anything they had yet seen, they were afraid. As she began to flex her magical muscles, they were terrified, perhaps rightly. Fear, though natural, leads to mistakes however. Rather than show her that she must learn to exercise restraint on her own and encourage her to learn how to control her powers, they feared for their lives, and so shipped her off into isolation.
Now, in a strange way, I think Syndra was happy about this. On her end, think of the consequences of her childhood. As she grew older, Syndra quickly realized that she had a natural gift for magic. It is not likely she completely understood her power, but Syndra knew full well of her potential, even at an early age. Because of this, her powers grew exponentially.
Sadly however, this power did nothing to help her socially. Normal citizens were likely very afraid of just what this little girl could do. I find it very likely that she was socially ostracized for her talents. There was something unatural, unbalanced about this girl. As we know quite well, Ionians prefer their balance over anything. This girl did not belong here. As such, I have a feeling that she was treated very much like a demon.
These sentiments undoubtably affected Syndra greatly. Out of spite perhaps, she grew stronger still. If they refuse to accept her for how she is, so be it. Afterall, she has a talent that none of them could ever hope to match. One day they recognized that fact.
After an unknown incident, the elders of the village finally deemed that Syndra was a danger to their little society. They took Syndra away one day, to a remote temple. Her powers were deemed beyond the boundries of what they understood, so they turned to the old mage of the temple.
Now, although the old mage helped Syndra, he is undoubtably a gray character. Rather than allow Syndra to exercise her full strength, he limited her power very early on. No doubt, that if given time, Syndra's power would have far out matched his. But is this a bad thing? Must the master always be stronger than the student? Without permission from Syndra, he sapped her strength.
Yet, surely there was a better option. Knowing that her power was beyond his, he could have just as easily passed her onto a teacher that was better than he was. Obstinately however, the old mage simply weakens her to keep her powers in check. This proved to be folly.
When Syndra finally reached the boundaries of her power, she was left frustrated. Day after day, her training proves nothing. The power that she had felt deep inside her since childhood was gone. Having shaping her very identiy around her powers, this had to be a truly nasty shock. Syndra knew that her potential was greater than this, yet every effort was fruitless. At last, the old mage finally told her the truth.
I can hardly blame her for being extremely pissed that her powers were limited. The analogy was brought up that a child would use a training sword if he would want to be a warrior when he grows hold. This holds true for a child with an idle toy. But consider this.
What if you are, say, a good runner. It is your life, it is how you define yourself. You can run faster, harder, and stronger than almost anyone. But you lack the running technique. Your stride is sloppy and you run into people. Irritated, your parents hire a personal trainer to avoid getting sued by the people you knock down. You learn the techniques of running, but you suddenly find yourself more sluggish than usual. The personal trainer is the culprit! Given that running is your life, you want answers. The personal trainer responds that he limited your athletic abilities because you were too quick to keep up. Furthermore, he will keep limiting you until you master your running techniques or he'll make it so you can never run again, lest you hurt someone. Your refusal of this unorthadox personal trainer is met with a baseball bat to the legs. They shatter, and your running career is over.
This is Syndra's situation. Imagine that her teacher did take her powers away. What then? Her entire life has been based upon her magic. Second, she trusted this man. He was her mentor. The elders had always hated her, but this man had gained her trust. The fact that she has been betrayed from the very beginning of her studies is undoubtably a shock. This was no school. This was a prison. To blame her for wanting to leave it is unrealistic.
But no, the old mage can't do that. Surely this young woman is a danger to society, and has to be kept under lock and key! What would happen if she were to leave the temple? Rampages, death! No, the only logical option is to break her metaphorical legs and nullify the only reason for existence so far in her life.
Rather than give him the chance to do so, Syndra flies into a rage. She kills the old mage in an act of passion. All of her life, fear and tradtion has limited her powers. If she was born in any other country but Ionia, her gift might have been accepted. But no, instead of fostering a gift they treated her as if she was possessed by a demon. A curse, a vile pox to the joys of balance. Send her away, seal her off until she's not so threatening! Who could blame her for not wanting to return to this.
Although the Ionian leadership was never mentioned, it is doubtful that they knew nothing of this. A girl of tremendous skill and power at her age isn't a quiet matter. However, they were content to let it happen. Now when that she's older and has ripped a temple from the ground, one can consider it logical that the Ionian leadership is not happy. Syndra is an enemy of the state. Like her dead master, Irelia and Karma are both souls who wish to see her gone. She is a danger to the state. Unstable and unbalanced.
Perhaps this why she joined the League. In order to protect her own powers, she fights as a champion. Her influence that she accrues keeps her from being arrested. She is afterall, a champion and is therefore allowed certain privileges. Though they limit her on the Fields of Justice, they do nothing to stop her outside the Fields.
Now, who's at fault here? There were many times that Syndra could have become a far more benevolent character, but time and time again she was left at odds with those above due to their actions. At the beginning of her story, the only thing she did wrong was practice "recklessly" and for having too much innate ablity. Then, Syndra was left at her wit's end with her mentor. It was either push or be pushed. If Syndra hadn't of pushed back, she would have never have become a champion. Likely after her outburst that day, I would wager that the old man would have completely nullified her powers for good.
Balance in all things.