The Silvani have only recently appeared on the world, or at the very least, society has only just now become aware of their existence. These creatures appear as humans or elves, depending on the population of people that live around the forest. It is unknown exactly how they are “born”, but the accepted theory is that when a forest believes itself to be in danger, or that it may be in danger in the future, it will create a Silvanus from a combination of bits of essence from each living being in the forest. As such, Silvani resemble dryads or tree nymphs in purpose, however the Silvani are not bound to stay in the forest, and most often don’t - they are the voice of the entire forest, to travel and live among the “intelligent” species of the area, sometimes to mediate issues, sometimes to fight those that might harm the forest or the creatures therein, and occasionally simply to live as one of them, in wait, as it were, until the forest is in need.
Since they are beings of multiple essence, they often have features of the various creatures, and occasionally assume their forms, and always have the natural ability to communicate with almost all natural animals (artificially created creatures like golems, or unnatural creatures like demons, are not included). They also usually have a good deal of ‘magical’ power derived from their extensive connection with nature, though the use of these powers is as natural to them as breathing.
Silvani are born as infants at the base of the eldest tree in the forest, and are often tended by dryads, forest nymphs, or sometimes wolf packs, though more usually a combination of all the forest creatures, as they can converse with any of these on a very basic level even at birth, and it strengthens with age. Like dryads, Silvani grow to a certain point, usually representative on some level of the age of the forest itself, and will live as long as the forest remains standing.
Likely the strangest thing about the Silvani is that they are not always aware of exactly what they are. They are universally born, and always grow up among the creatures in the forest, though occasionally one will grow up like this without realizing that he or she was not born like the other people in the towns around them. They know, certainly, that they are not human, or not an elf, but they do not know what they are, and don’t take the time to wonder exactly what that is. Also, they see their powers as perfectly natural things for someone to have. Again, they realize that other people do not have these powers, but they don’t find it odd that they do. Not that they aren’t intelligent, it is simply a case of growing up with something and believing it is normal. Still, whether they know why, or not, all Silvani are somehow protecting their forests, the warriors of the trees.
Interaction: There is almost never more than one Silvanus in any forest, unless it is a forest that stretches continuously for miles upon miles. They are constructed, if you will, like I said, from a small bit of essence from just about everything in the forest, rather than just from the spirit of a single tree, like a dryad ((I believe this answers another question as well)).
Awareness of others: As I said, there are very very few of them, and they are widely spaced, so there is very little interaction. Also, like I said, some of them arent even aware of what THEY are, much less aware of others of their kind.
War: Same reason as the last two. In a time of war against the forest, or in case the forest were to take sides in a dispute between say, humans and elves or humans and another group of huamns, the Silvanus of that forest would be a sort of a general, with their ability to link themseleves on a certainl level with every natural creature born in the forest. I think I would describe them as a kind of avatar for the collective conciousness of the forest
As for the thing about advisors, it would most likely be in terms of a dispute over lands of the forest claimed by various groups. The forest, and therefore the silvanus, would remain largely neutral in that sort of thing, but they would usually attempt to avoid a war where possible - war is rarely kind to the land upon which it is fought.
Finally, they can leave the forest because that is half the point of their existance. They are not necessarily an extension of a spirit, but an independant collection of bits of spirits. They have a very deep connection to the forest, but they CAN live without it.. Rarely do they stray from their forest, but they ARE able to leave