The Bonding Sickness is a sickness/disease that affected both humans and their spirit animals, caused by bonding without the Nectar or Bile. The bonding sickness is different for everyone. It was a pandemic that spread after The Evertree was damaged in the first Devourer War. It was most common in Stetriol due to the island not having access to the Nectar, leading to the creation of the Bile; it cures the bonding sickness, but the trade off is being a prisoner of its effects and Gerathon's mind-control. If the bonding sickness is not cured, the victim will become extremely sick or insane, which is sometimes followed by death. People were freed of the bonding sickness when the original Evertree was destroyed by the Great Beasts in The Evertree (Book). When the Bile was introduced to Stetriol, the islanders took it, mistaking it for a blessing.
- King Irwyn believed that killing his spirit animal would cure his bonding sickness, however, it only made it worse.
- Shane told Abeke in Wild Born that he watched as his family was destroyed by the bonding sickness, which is true. However, he said that "he was one of the lucky ones, and other family and friends weren't". This isn't true, as he had a Bile bond. He summoned Grahv from the Bile, he didn't have him before drinking the Bile.