So I just listened to the Wendigo episode and was excited to find this discussion, even if i'm late to the party.
I've seem to remember reading a few different things over the years, I couldn't tell you where, so perhaps they're apocryphal, but still pretty cool. One is that Wedigo was either heralded by or brought with it intense sub-zero cold snaps, and blizzards. Another was that they were wind spirits of vengeance and that their name meant spirit who runs through tree tops. I also kind of remember them being associated with the sound of howling winds and trees exploding in the cold (if you've never heard it, it sounds like a shot gun) Again I can't account for the veracity of those story's but they've been floating in the back of my head for years.
I also remember reading a story with in the last couple years about a man in Cananda who was either tried for being possessed by a Wendigo, or at least claimed he was after he and his family were snowed in their cabin for several months and he...well, you know. If i remember correctly it was as recently as the late 1800's or early 1900's and it was in the newspaper.
I'm not quite skilled enough for stat blocks at this point in my DMing career but creatively this got my mind moving. So we have these different aspects, sometimes they look like skeletal people and sometimes monsters, sometime they're spirits and can posses people and sometimes they're giants. It is either a curse or it can curse others. So it got me thinking.
I have this image of seeing that skull with those antlers peaking between the high peeks of ancient snow covered pines. Almost like a Myazaki image or Japanese wood cut. Or maybe the party is approaching some small northern mining town in a blizzard, fighting against the wind and snow, trying to find shelter and looking up to see its giant skeletal form hunched over some small cabin, reaching though the roof with its ghostly claws only to look up and disappear when it sees them. When they break into the cabin they find a man has slaughtered his family and consumed them.
My thought is, what if there is only 1 Wendigo and its this giant, semi substantial form that is only really visible in heavy snows. Some creature that was cursed ages and ages ago, then banished to the elemental planes between wind and ice. Frostfell in Forgotten Realms terms.
The curse has to be related to greed, hunger, the severe cold and perhaps its animal appearance. 00dlez had a great idea about a greedy merchant in another thread. I like taking that and putting it in the far north, in some barbarian tribe. Maybe some Cain and Abel type story, part of a tribes origin myth? Perhaps the deer aspect is related to the specific event?
Part of its curse is its banishment (maybe not to the elemental realm but stuck between them?) part is this hunger it can't sate.
If we add that vengeance aspect to it, then perhaps part of its curse is only being able to eat the flesh of those who have eaten the flesh of their own kind. So it spends ages starving, trapped in the cold between worlds, waiting for some one to go hungry and eat their dead. Growing angrier and more and more Malevolent, perhaps even influencing the weather on a local level, hoping to create the right circumstances. But once someone does cross that line it finds them, and punishes them by eating them it self. As it consumes them it gains power and over the millennia its grown, in physical size, in influence and in its ability to slip the bounds of its curse. By the time the players find it, its ancient and 30 feet tall and when it touches some transgresser, they become a proxy for it, consuming flesh on its behalf, essentially plumping themselves up for the Wendigo. As they consume more and more, its hold on them grows, these are the emaciated skeletal people that "chew off there own lips". They continue to take on aspects of the Wendigo until they resemble them completely and it has complete control over them. They are at the height of their power in this stage, but it is at this time he finally consumes them and their souls. In this way his influence and power are beginning to grow exponentially.
Perhaps the players can only truly defeat the true Wendigo if they battle it on the elemental planes?
This idea could fit the three tier model discussed earlier in this thread to, which I like a lot.
Also While I was working on this an origin story popped into my head.
Bothers where snowed in during a severe storm, subsisting on a single deer they'd hunted. When the food ran out one brother found the other the other had been secretly hording meat, and grew enraged and killed him. When the rest of the tribe found them after the snow melt, they found the surviving brother well fed. The other's head had been replaced by the deer skull, the rest of his flesh consumed. The surviving brother was cursed to never be sated and only ever consume the flesh of those who had eaten the flesh of others. He was transformed to look as he'd left his bother and banished to a place where it was always frozen.
Also I could see this concept fitting into a campaign as a side effect of the players previous accomplishments. Like in the process of accomplishing some other quest they accidentally destroy the wards that keep the Wendigo at bay, so when they return to the village its been over run by blizzards for months and half the homes in the town have succumbed to cannibalism to survive, giving it several proxy's.
I'm looking forward to a point when i can work this into the campaign I'm starting.