The latest GW2 advert
Speculation:
It’s been theorized that the Sylvari are actually minions of the Jungle dragon (hence why they’re the only race that can’t be converted to minions of the other dragons), and that the pale tree is a dragon champion who, like Glint, has rejected their master due to long interaction with the other races while their master was sleeping.
If so, the “true nature” that the Nightmare court is searching for (but so far failing to find) is the way they would behave if they were still under the control of a loyal champion.
What if what Scarlett saw in the mists has to do with the above? Maybe she’s kittened at having to choose between being a puppet of the pale tree or being a puppet of the Jungle Dragon and this whole thing is about her trying to find a way to “cut her strings”? Would explain her fascination with mechanical creatures, which seems to be like trying to eliminate her organic Sylvariness.