German Shepherd dog (GSD). He simply followed her into her building and then into her apartment and stayed on. The only problem was that once he settled down, he would have a tantrum if she left him alone in the flat.
He would turn the place upside down while she was away, to show how upset he was. Finally, she had to give him away to someone else who could manage him better.
Our family also had a GSD, lovingly named Devil. He was nominally the 'family' pet but there was no question that there was one person who came first and foremost for Devil: my mother-in-law.
Everyone else came later even though he was affectionate to all, including our baby son. If his main person happened to be sleeping, no one was allowed to come anywhere near her. Poignantly, Devil passed away a few days after her, both due to cancer, 31 years ago.
Memories of Devil came flooding back while reading about the travails of Commander and his predecessor Major, both GSDs who have been sent away from the White House after repeated incidents of biting (or, as some have called it, «attacking») Secret Service agents posted there to protect US President Joe Biden and his wife Jill, and other staff too. Both dogs probably regarded those 'outsiders' as suspicious who got far too close to their «Protectees».
In a strange but utterly understandable way, the GSDs and those close protection agents were treading on each other's turf as both regarded themselves as the primary security guardians of the US First Couple. In fact, those GSDs probably consider all White House staff as potential threats as dogs have an astonishingly good radar to suss out the difference between staff and family.