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"Where is that idiot?" asked Dumbledore. "He was supposed to be here twenty minutes ago."
"I don't know, headmaster," said Minerva McGonagall. "Hagrid's not exactly a paragon of reliability."
"We can't keep the street blacked out indefinitely, someone's bound to report it to the muggle authorities."
In the distance there was the roar of an engine, rapidly getting closer. "That sounds like Black's motorcycle," said Minerva. "He seems to think that Muggles won't notice it flying if it makes the right noises."
A motorcycle appeared, but it wasn't flying. It screeched around the corner and stopped about five yards from them. A tall powerfully-built figure wearing a leather jacket and dark glasses but no crash helmet climbed off, put it onto its side-stand, and turned to face them, saying "Albus Dumbledore?" It wasn't Hagrid.
The stranger pulled something from its back, a muggle weapon, a... a gun, that was it. Without taking any apparent time to aim he pointed it at Dumbledore and fired. He was dead before he had time to react.
"Minerva McGonagall?" The stranger shook the gun and turned towards her, and she raised her wand and said "Stupefy"
"Minerva McGonagall?" The stranger ignored the spell completely and added "Positive identification." It fired again.
Vernon Dursley opened a window and looked out, shouting "What's the idea of letting off fireworks? Some of us are trying to..." A bullet between the eyes interrupted him, and his lifeless body fell from the window. An irrelevant interruption. So was the death of Petunia Dursley, when she rushed from the house to see what had happened to her husband.
Its first targets eliminated, the T-101 waited patiently for the arrival of Hagrid and Harry Potter, ready to terminate anyone else who interrupted. There would be no effective magical resistance to the rise of Skynet.
Harry Potter / Terminator