Despite its unspoiled appearance, Pandora is not entirely free of Morgoth's shadow. The discordant theme he wove into the Music in the beginning afflicted the whole universe.
The difference between Earth and Pandora is that Morgoth never came to Pandora. He did not spend ages there spreading death and destruction, pouring his malevolent influence into the land. He sunk most of his power into Earth, permanently contaminating it; much as Sauron did with the One Ring.
Pandora is free of this poisonous essence. Instead, it was Yavanna who poured her power into its land. Instead of malevolence, she poured out her love. Instead of a will to destroy, her will was for life to grow and thrive. Instead of a desire to dominate, she wished to see her children grow strong and come into their own in a world free of oppression.
Being thus governed by the influence of a pure Valar, Pandora is much like Valinor. Although evil and misfortune can occur there, they are not the normal state of affairs. Evil does not propagate easily. But unlike Valinor, humans are not barred from journeying to Pandora. In this way, the corrupting essence of Morgoth may be imported, bringing horrors and sorrow inconceivable to the Na'vi. Greed, hatred, wrath, torture, vengeance, mass destruction, deception, betrayal. Trauma of the soul. Broken relationships that resist all attempts at healing. Perverse attitudes and selfish motives that lead to destruction.
The Na'vi recognize this intruding influence for what it is - demonic - but because of their relative innocence, know not how to combat it. Their ways of resolving their own conflicts often fail under the sheer weight of evil that humans carry with them.
Hope remains in that the spread of such corruption is limited on Pandora, as it is on Valinor; because of the lack of corrupting essence within the land itself. Conversely, Pandora can have a purifying influence on humans whose hearts are open to it; much as Valinor had a healing influence on the few mortals who were allowed to journey there.
Those humans with an open heart see Pandora as a paradise, despite the dangers it holds for them. They feel a calling deep inside, from that quiet part of the human spirit that longs to return to a primordial state of innocence. But just as Ar-Pharazon and his army felt no reverence or awe upon reaching the shores of Valinor; those with hard hearts, who are content in their ruined state, can see no beauty in Pandora - only danger, hostility, and an opportunity for conquest.
Humankind has declined over their many ages of exposure to the corruption of the earth. Their lifespans are a fraction of what they once were. Long ages of sin and decadence and many centuries of indolence have left them weak in body and dulled in spirit.
The Na'vi do not suffer these ailments. Their lives are shorter than humans' were at their awakening, but much longer than any human since the line of the Dunedain failed. They are not plagued by disease and disorders of the body as much as humans are. They cover their bodies only for basic modesty; they feel no need to cover more of themselves because of sexual perversion, deformities, or low self-esteem. Such issues are rare and terrible to them; not everyday concerns. Marriage remains a sacred thing to the Na'vi; to violate that bond is unthinkable.
Love remains pure among the Na'vi. This is not to say it is never complicated. Two men competing for the attention of the same women may come into conflict. They may come to blows. Long-standing friendships may be strained, or even broken. But for the conflict to escalate to serious violence; bloodshed, rape, murder - is unheard of. To humans such a thing is evil and tragic, but not inconceivable; for their history is filled with such wicked deeds.
To the Na'vi, children are seen as one of the greatest blessings in life, and their proper care is a sacred duty. Na'vi parents may be firm and sometimes harsh, but almost invariably hold a genuine, warm-hearted love for their children. Abuse is rare, and swiftly dealt with. In the rare case that parents are unwilling or unable to give their children proper care in all respects - physical, emotional, and spiritual - the leaders of their clan may demand they turn the child over to a family who is willing and able to care for them. No child is to be left without a family.
Life on Pandora is hard, but it is pure.
The perversion of love is worse by far than the despoiling of the land, for it can lead to the ruin of all things.
Consider the orcs: Whatever love dwelt within the heart of an orc was only a twisted reflection of true love; always tainted, always under a shadow. An orc father may love his son, and wants him to become strong in body - so he beats him. If the son fights back, the father praises his tenacity, then beats him harder. The father wants his son to become strong in mind, so he speaks harshly to him and ruthlessly criticizes everything he does. An orc loves his tribe - so he leads a war party to destroy a neighboring tribe so they can never become a threat.
In this way, nearly any act of love an orc is capable of will be twisted into something destructive.
Humans are not orcs. They retain a capacity for wisdom and righteousness that was almost wholly purged from that ruined people. But all the orcs' wicked tendencies, all their perversions of love, are found in abundance among humans. It is like a deadly virus that has become endemic.
Na'vi cannot catch Earth diseases, and humans cannot be sickened by the few illnesses on Pandora. Their bodies are too different. But the spirits of the Na'vi are made in the image of Eru Illuvatar, the same as humans, and they dwell in the same universe under Morgoth's shadow. They are not immune to these contagious diseases of the spirit, even though they and their world are blessed with greater resistance.
When humans came to Pandora, they brought spiritual disease like the sailors who carried smallpox to the Americas. Hate, resentment, distrust, and fear; of a degree the Na'vi had seldom known, began to proliferate among them.
Neytiri te Tskaha Mo'at'ite suffered greatly from the humans' depredations. She was saddened and angered by the invasion and defiling of her people's land. Her sister was killed in front of her while she was still a child. Her ancestral home was attacked and destroyed, killing her father and many other members of her clan. Her own husband, Jake Sully, had been pivotal in the planning of this attack before he came to know her. He repented and she forgave him; but the lingering resentment in her heart did not leave room to forgive the orphaned son of the enemy commander, only an infant at the time of the atrocities.
Miles was too young to return to Earth, so he remained on Pandora. As he grew, he came to love the forest and hate the unliving human dwellings he spent his early years confined in. He was favored by Yavanna. He contradicted many assumptions about human life on Pandora. Growing up in the low gravity should have made him weak and frail, but he became taller and stronger than normal. The creatures of Pandora should have reacted to him, an alien, with hostility and fear - but they did not. He could look an ikran in the eye without challenge.
The human couple charged with raising him were distant and uncaring. Despite their decision to stay on Pandora, they remained rooted in the ways of Earth, and they could not understand this child born of another world. The boy grew up around the Na'vi, learning their language, adopting their customs, and becoming close friends with Jake and Neytiri's children. He was true and strong of heart. He rejected his father's name, going instead by his nickname, Spider.
But it did not matter to Neytiri that he was ashamed of his father and forswore his ways. It did not matter to her that he loved her children, and had no true family of his own. Her heart remained hardened against him, even if her own people's teachings would condemn her for it. No matter how loyal he was to her people, all she could see in the boy was the evil of a man he had never known. He passed through his childhood and adolescence under the shadow of her resentment.
When a new invasion came from Earth, his foster parents proved wholly treacherous; betraying the Na'vi and abandoning him. This only cemented his loyalty to the people he loved. From then on he lived in the Na'vi camp with the few other humans who remained. But still, Neytiri did not acknowledge him. When he was captured by the invaders after helping her daughter to safety, she turned her back on him.
With almost any other human, her treatment of him would have lead to a lifelong enmity, fear, even hatred. But Spider was a child of Pandora - the first human ever born on a world not thoroughly poisoned by Morgoth. His life was darkened by that evil, but not dominated by it. His heart remained pure.
He acquitted himself valiantly in every way. His loyalty never wavered, and he went on to accomplish great deeds of heroism in defense of his adopted people. He endured under torture and months of captivity without ever betraying them. He pleaded for the lives of Na'vi he had never known. He leapt into action to turn the tide of a battle, rushing selflessly into danger again and again to save a family he thought would never accept him.
After the dust of that battle settled, the full weight of his pain and his deeds began to impress themselves on Neytiri's heart. Finally, she begin to see him for who he was, and not who his father had been.
The arrival of mankind brought terrible darkness to Yavanna's refuge. But mankind is not Morgoth. They cannot corrupt a world as thoroughly as he did. The seeds of his corruption may take root beyond Earth, and the trauma of their planting is often difficult to heal. But they will never thrive as they did where his shadow was darkest. The light of the Valar shines on Pandora, and the darkness cannot extinguish it.