Gyrus Dearborn had become an Unspeakable like his parents and aunt. He was an Unspeakable in the Brain Room.
During the First wizarding war and even before that Gyrus father Caradoc Dearborn had been ally of Albus Dumbledore and eventually became a member of the organization known as the Order of the Phoenix.
Before the end of the war Gyrus was captured by Death Eaters with the aide of former Unspeakable Augustus Rookwood. Gyrus was tortured but survived. His body had given out but not sanity and sense of self. Recovered by Hit-Wix he was immediately taken to St. Mungo’s Hospital for Magical Maladies yet healers and medi-wix were horrified and baffled by his symptoms. Saul Croaker the Unspeakable of the Time Room put the young wizard’s body into a stasis to stop the effect of the Cruciatus Curse. Broderick Bode and Peony Dearborn transported him to Brain Room.
A fail safe and precaution for the Unspeakables who expertise in the Brain Room is storing their own thoughts and memories essential taking a piece of themselves. Hence the pearly white brains visitors see when entering the Brain Room.
With help of his wife, a Healer and Time Unspeakable Saul Croaker, Gyrus slowly put himself back together. Gyrus resides in the Domain of Isolation an unplottable location in which Unspeakables live and train. When outside he can shift to a permanent corporeal human form. Sometimes a striking phosphorescent giant brain that surprised his aunt, wife, and son.
Human Form by Janusz Jurek