Jareth’s merger with the divine phoenix ash is still unstable at best — they have become more closely bonded over time and eventually his body will adjust to the presence of the foreign entity, but currently he has some recurring issues due to their union.
The biggest being that sometimes he can become very disconnected from reality — dissociative, while in this state he often feels as if his body is not his own. This happens most often after intense combat, when his mental and physical states are pushed beyond normal limits — he can have difficulties recognizing people he’s familiar with, get lost or disoriented in places he knows well, or collapse if he continues to overwork himself.
This symptom is a good indicator that Jareth has been pushed past his breaking point even if he claims otherwise; he is extremely stubborn when it comes to taking breaks and has a blatant disregard for his own health due to the nature of his upbringing. As a child he was often pushed to absolute extremes — forced to make difficult decisions and to cast his own comfort aside for the “sake of the family”. He does much of the same now, doesn’t know how to operate in a balanced manner. Although he gets scolded by the other members of the Crux, it doesn’t change his behavior — Jareth doesn’t really know how to relax or take a break. He gets very jittery if he’s not doing something.
If he’s been critically injured and lacks the energy to promote self-healing, he can be taken over by the phoenix, who would seek to protect its vessel by destroying anyone or anything that stands in its way. Notably, this has only happened a few times during battles with more powerful demons — it can be stopped if Jareth is awakened, but it’s risky as he could easily hurt someone he cares about under the influence of his power.
Some of the more minor side-effects include: musculoskeletal pain, headaches, shifting in the growth pattern of his wings, dysfunctional temperature regulation, exhaustion, insomnia, and lack of / complete loss of appetite.
