Besides dogs, pigeons also had an instinct for finding their way home, which was why people trained carrier pigeons to deliver messages.
Voldemort had once possessed a raven. At the time, everyone had thought the war was over and that he would not return, just like last time.
Pomona, like Ginny, had also had her body controlled by him. She had no memory at all of that time. When she came to, she found that their temporary lodgings had become a luxurious palace—decorated to Slytherin's taste.
Hogwarts had been like home to Harry, until he gained Sirius as a godfather and Grimmauld Place as the headquarters of the Order of the Phoenix. He had spent Christmas of his fifth year there. If not for safety, he had not wanted to return to Aunt Petunia's house at all, despite their blood relation.
After graduating from Hogwarts, Voldemort had vanished for nearly twenty years. When he returned, he looked vastly different from Tom Riddle, and at the same time, his power had grown to heights beyond the reach of ordinary people.
He became the Dark Lord, with countless followers, and stirred up a frenzy in Britain during the seventies.
Someone like him would not live in a cave, nor would he live in a house made of animal skins like Isolt. Pomona also believed that Helena would not fail to find herself somewhere to live.
Severus also had his own residence somewhere in Albania: a bunker left behind by Germans during World War II. Pomona had been there, but she did not know its exact location.
Perhaps to make it easier for their "master" to summon them, full-member Death Eaters like Severus lived near a possible castle. Sybill Trelawney had once said in a prophecy, "The master and servant will reunite tonight."