In terms of characters getting high off aether, maybe only the really high-born (with fire in their blood) can use it as a drug without dying.

We note that the pools of aether in the ground are actually left over from the last time the Deadwood consumed everything. This is probably hinted at when, deep in the Deadwood, someone slashes at a tree they find is warm and discovers aether leaking out. Someone says it's collecting aether from underground? Serinth answers that they are creating it.

Animals that are addicted to aether glow from their eyes, tongue, and paws. Biolumisecent. Like that owl from Secret of Nimh or any of that furry shit. Eventually (in the present Majordomo describes him this way) Kae'Kil sports some of these features, his eyes and tongue and paw glowing from aether build up, Majordomo wonders how much he has to take now just to keep himself alive. (It would be very interesting if eventually we see him going through withdrawals, he can mention to Heyoke in Cubs in Zarkhan that aether isn't worth getting addicted to, apparently he didn't follow his own advice.)