pathological

adj

1. Pertaining to pathology.
2. Relating to, amounting to, or caused by a physical or mental disorder.

   “Paul Canning's performance as Julian gives the character an emotional center that is not in the script: He is vulnerable without being pathological, needy without being pathetic.”

3. Having properties which are counterintuitive or difficult to handle.
4. Having properties that cause unusually bad behaviour, especially regarding correctness or performance.