Although generally found alone, yao guai exhibit a gentle, familial bond toward one another when found together, provided they do not feel threatened by the observer's presence. Yao guai will attack nearly any other creature or person they encounter, including deathclaws. However, yao guai have been known to be occasionally friendly towards bloatflies.
They can most often be found in pairs, or alone, wandering the Capital Wasteland, mostly in and around craggy, hilly places, or in caverns. They also seem to appear more often at night than during the day, suggesting that they are nocturnal.
There are some wasteland scavengers that have somehow managed to domesticate yao guai for protection and companionship. These will not attack on sight and can be approached, although they will defend themselves and their master if threatened.
Yao guai attack by using running pounces followed by slashes and bites after closing the distance to their target. Like all creatures that have pounce attacks, they can't pounce with a crippled hind leg. However, even after crippling one of their limbs, they will resume charging after a split second. Yao guai have a high Perception, and can therefore become aware of the player even when not in a direct line of sight.
According to a Fallout 3 loading screen, the yao guai are descended from the D.C. area's black bears. Considering their ragged and rotting appearance, along with the famous bear Ruzka still living in Point Lookout 200 years after the Great War, it's possible that yao guai have undergone a sort of ursine ghoulification. However, the presence of yao guai cubs in Zion Canyon indicates that the species is still capable of reproduction, unlike human ghouls.
When one is extremely close to a passive yao guai, they can be heard to have a wheezing, raspy breath. This can also be heard by entering the Pip-Boy menu whenever a yao guai approaches or nears the Lone Wanderer.
Yao guai are not as deadly as deathclaws or some of the Wasteland's other inhabitants, but can be extremely deadly to lower level characters as they occasionally spawn south east of Megaton near the crossing into Washington, D.C..
Yao guai can sometimes be seen taking out some Talon Company mercs in a random encounter. Sometimes after the Lone Wanderer encounter this, they won't attack him/her at all.
If a yao guai encounters an Outcast patrol under the over pass closest to Megaton and the Outcasts kill the yao guai there, it can become a recurring encounter as both the yao guai and the Outcast patrol will respawn approximately every 3 game days.
In Chinese, yao guai (妖怪) simply means "monster". In Chinese mythology, "yao guai" are physical manifestations of the spirits of mistreated animals, or fallen divine animals.
Three Dog's advice on yao guai is simply: "Don't feed the yao guai". This is a reference to the adage "Please don't feed the bears," a saying commonly found on signs in parks, zoos and other areas populated by bears.
ps3xbox360 Yao guai seem to be unusually prone to physics glitches, which may cause them to fly or launch when killed. This is most common when one is killed mid-air, usually with a combat shotgun. [verified]