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".
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.
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 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.