Miss Peregrine tells Jacob that if "the children loiter too long on your side of the loop, all the many years from which they have abstained will descend upon them at once, in a matter of hours".

Sergei Andropov, the folding man from the carnival in the tourist loop, wanted to build a peculiar army to fight the wights. At the time he met the children, he had six "soldiers" in his army.

When "Miss Peregrine" is released from her bird form, the children discover that it was really her brother Caul. Although unable to manipulate time as an ymbryne does, he had the ability to turn into a bird of prey and "impersonated" Miss Peregrine in order to locate Miss Wren.

Described as "the most depraved and dangerous slum in the whole long history of London", Jacob and Emma hire Sharon to take them to Devil's Acre where they believe their friends are being held captive.

Myron Bentham is Miss Peregrine's and Caul's brother. Although he seemed to be helping Emma and Jacob, he eventually betrays them to get to the Library of Souls.

PT is Mr. Bentham's trained grimbear.

Mr. Bentham and his brother, Jack (Caul), built the Panloopticon as a way to connect loops around the world. "With the Panloopticon, the initial, arduous trek of first contact has to be made only once, and every return trip thereafter is instantaneous."

The wights make ambrosia out of stolen peculiar souls. The "ambro" gives peculiars enhanced abilities, but as they become addicted, their own ability "wears down to almost nothing".

Mother Dust uses her peculiarity for healing. As she rubs her skin, part of her is turned to dust which she uses to heal sickness and injuries. The dust also has a sedative effect which saves Jacob from becoming hollowgast food.

The peculiars discover that when the ymbrynes collapsed the loop at Abaton, any peculiar that was present had their true age reset. They would then age as a human, one day at a time, allowing them to travel to future time loops without aging forward.