Guild Wars 2

Sylvari As Seeds
Ultimately, I believe that the Pale Tree wakens sylvari because she is trying to reproduce. But, as I previously noted in my post, “The Other Tree”, there is no guarantee that any one sylvari will actually germinate. (Thus far, Killeen is the only viable candidate for germination, although her ultimate fate is yet to be determined.) Still, if we were to assemble all of the sylvari and attempt to sort those most likely to become trees from those that are not, we could begin by separating Dream sylvari from Nightmare sylvari. Nightmare sylvari are excluded because they represent “bad seeds”, infertile for any number of reasons, but most likely due to some kind of disease or malformation. The idea that Dream sylvari represent fertile seeds and Nightmare sylvari infertile seeds is further evidenced by the behavioral characteristics of sylvari attached to each. The Dream motivates sylvari to leave the base of the Pale Tree, (for the most part) cooperate peacefully with other sentient beings, serves as a repository of knowledge gathered by each seed led by it, and also serves as a database of the locations of each seed (this latter detail would help it to keep track of where seeds have “fallen” and may also help to explain why the Pale Tree, urged by the Dream, would be so interested in learning of Riannoc’s final resting place). All of these things combined significantly increase the Pale Tree’s chances of reproducing successfully.
In contrast, although the Nightmare appears interested in the reproduction of the Pale Tree, it is more concerned with substitution. Hence, rather than simply killing and planting a Nightmare sylvari, Nightmare Courtiers not only strive to turn the Pale Tree to Nightmare, but also seek out other great oaks (such as Malyck’s tree), attempt to nurture other species of tree into existence (Faolain’s tree), or abandon trees altogether in favor of other species of plant (the Tower of Nightmares and it’s seedlings). In other words, the Nightmare doesn’t take from the stock of Nightmare sylvari at it’s disposal to try to find a substitute for the Pale Tree because they are infertile seeds. Moreover, it will never truly be able to successfully reproduce a great oak associated with the Dream because those Dreamers that it attempts to turn are rendered infertile in the process.

Are Nightmare Sylvari Connected To The Dream?
Of all of the questions that we could ask, this is probably the most important. Unless it is explicitly stated, we simply cannot be sure whether Nightmare sylvari remain connected to the Dream. There are various sources of information regarding the state of Nightmare sylvari in relation to the Dream. One of the foremost sources is a conversation between sylvari in Twilight Arbor EXP.
A sylvari refugee who has endured the tribulation of the Nightmare Court is advised by a Warden thus: “I caution you against departing too soon.” Confused, the sylvari asks, “Why? Will my nightmares hurt the Pale Tree?” The Warden attempts to reassure his injured fellow, “Not as such, those experiences are already a part of the dream, but you’ve been through a terrible ordeal.”
Whilst this can be interpreted as proof that Nightmare Courtiers are in fact connected to the Dream, there are several reasons why we need to exercise caution when drawing such a conclusion. First, the Warden is not addressing a Nightmare sylvari – or at least, not a sylvari who openly identifies with the Nightmare. If we were to replace the sylvari refugee with a captured Nightmare Courtier and a similar conversation were to take place, this would greatly strengthen the idea that Nightmare Courtiers are connected to the Dream.
Second, the Warden is hesitant to allow the sylvari refugee out of the arbor, although this seems counter-intuitive to any recovery process. Why would you want to leave refugees in such a perilous situation, especially when there are not only three powerful Nightmare Courtiers nearby but also the general area is simply not conducive to good spirits? If you really wanted the refugees to recover, surely you would send them to the Grove – a remedy suggested by sylvari stationed at nearby Falias Thorp.
Third, there is every possibility that these sylvari have been affected by Nightmare but just don’t realize it. In essence, they may already be turning, especially when we consider that one states how he has nightmares and another states that she can still hear a cacophony of diabolical voices in her head. In other words, both sylvari have probably been recovered from conversion pods (the latter has been) and may already be disconnected from the Dream. The Wardens may be holding them at Twilight Arbor to monitor them, in case either turns, in a process similar to quarantine.
But how could sylvari be turned to Nightmare without realizing it? In my opinion, sylvari may not know the difference between the Dream and the Nightmare because they are so alike; if we posit that the Nightmare is a form of Elder Dragonic corruption, the “hive mind” mentality of Nightmare has much in common with the inter-connectedness of Dreaming (I am not stating that Dreamers are part of a hive mind).

The second-most important source of information on the relationship between Dream and Nightmare is provided by the Pale Tree herself, who when asked states that “[o]nce beloved to me, as you are, these poor misguided children (Nightmare sylvari) have – through free will – taken a dark path. Their disdain for Ventari’s words leads them astray and does harm to the Dream”. The question is how they do harm to the Dream.
Nightmare Courtiers don’t just engage in some kind of flagellance in order to harm the Dream, they also take Dreamers and torment them. They do this because eventually they can no longer taint the Dream with their own evil. Moreover, the Dream may not actually store memories of the evil delight taken by a Nightmare Courtier who kills his fellow sylvari; instead, the Dream may store the terror of the innocent victim, a powerful emotion that is not, in and of itself, evil.
But the state of Nightmare sylvari surely must be worse than that of the Soundless. When asked of the relationship between the Dream and Soundless, the Pale Tree answers that, through meditation, Soundless sylvari have cut themselves off from the Dream. How is it possible that the Soundless can be close to the outer fringes of the Dream, if in it at all, but Nightmare sylvari cannot? How is it reasonable to consider that although Nightmare sylvari are so vile that they would actually do harm not only to their fellows but also potentially to the Pale Tree, they are somehow closer to the Dream than the Soundless, who do not openly defy the tree or publicly promote acts of violence against their fellows? Indeed, if we truly were to ask ourselves, “Which sylvari are closest to the Dream?” would we not answer, “Those sylvari who submit to the Pale Tree and the Dream, as the latter is embodied in Ventari’s tablet?” And if you were asked, “Which sylvari are most likely either to be on the fringes of the Dream or completely disconnected from it?” would you not answer, “Nightmare sylvari” before you even considered the Soundless?

Why Would The Dream Kill Corrupted Sylvari?
Herein lies the problem. There is no easy explanation for this. If we view the Dream as a force working for the successful reproduction of the Pale Tree, we could then propose that it kills sylvari corrupted by the Elder Dragons because they have been rendered infertile seeds. The trouble is, if the Dream is prepared to kill sylvari for this reason, or a reason akin to it, why doesn’t it also kill Nightmare Court sylvari? For Nightmare Courtiers can be viewed in a similar way to corrupted sylvari – both have been rendered infertile in some way. Indeed, Nightmare sylvari are arguably as evil if not even more evil than any Elder Dragon minion.

Conclusion
In my opinion, we can understand the Dream as a force working for the successful reproduction of the Pale Tree and the Nightmare as a state of infertility caused by either disease and malformation or Elder Dragonic corruption. We should also be careful not to push the idea that Nightmare sylvari are connected to the Dream too readily, as there is every possibility that they are not. Finally, it remains to be seen whether the Dream actually kills sylvari rendered infertile by Elder Dragonic corruption. Whilst proposing that sylvari are killed by the Dream when the physiological symptoms of corruption become manifest (i.e. the corruption “sets in”) is an earnest attempt to understand why sylvari cannot be turned, it is yet to be confirmed in-game. I hope that with time, we can finally have a definitive answer.