At first, Harry wanted to brush it all off. Stop hiding under the invisibility cloak, find his friends, apologise for worrying them, and have a nice, complication-free trip to Hogwarts. Goodness knew he had enough going on his life. Did he have to make mountains out of molehills, too? The Weasleys could have been talking about anything. Perhaps even talking about some sort of safety precaution for the upcoming year, or be referencing Sirius Black in some way that Harry couldn't figure out, because he'd only heard the tail end of the conversation. Not to mention, he could have misheard anyway. He'd been eavesdropping through a wall.
His face burned with embarrassment and he nearly climbed up from the floor, jostling Hedwig's cage until she scolded him with one sharp noise, when a sudden thought struck him.
This compartment was utterly empty besides him. Carefully pulling his invisibility cloak around him, Harry tiptoed to the door and peeked out, into the compartment across from him, and for good measure (sliding out of the door just a hair), into the next compartments as well. Aside from the still-snoring, shabby man in the very next one, the back four were totally empty. The ones ahead didn't look particularly full either.
Harry trudged back to his spot, casting aside the cloak in favour of a disillusionment spell cast on the window instead. He stared out the rain-streaked window and brooded. What had Ron said, that first train ride? Can I sit here? Everywhere else is full.
Only it couldn't have been. Because there were less people first year than there were now, and the train wasn't even close to full now. Granted, he supposed that Ron could have meant there was no compartment that was completely empty and at least Harry was a fellow first year, but still. It was at least a bit odd, wasn't it?
Potter's fast friends with Ron! Dumbledore's ensured it!
But how could Dumbledore ensure a friendship by chance meeting on the Hogwarts Express? Unless Ron had already known who he was? He pondered this for a moment, scarcely noticing how the temperature began to dip down and the train began to slow. The twins had helped him. Had known who he was. Or guessed. But Ron had professed disbelief and uncertainty. It was hard to believe he would pass up an empty compartment or a chance to sit with someone who looked friendlier on a supposed prank by the twins. Then again, Harry was "The Boy Who Lived."
Harry sighed. All he was doing was coming up with more questions than answers, and it was making his head hurt. He rubbed fretfully at his scar before he realised the entire train had jolted to a stop. Goosebumps prickled on his entire body as the temperature lowered still more, and he breathed frost on the windowpane, rubbing it away and looking out. Everything seemed entirely ordinary.
Acting on some barely understood hunch, he grabbed his wand and stood up, but before he could reach the door, it slid smoothly open, a black-hooded, scabrous thing standing in the doorway. Icy breath filled the compartment and Harry clutched at his scar, gasping in pain as a brilliant flash of green light flooded his mind and all he could hear were desperate, anguished shrieks. He slumped to the floor, glasses hanging by one ear, as Hedwig hooted madly at the intruder, her wings bashing against the sides of the cage.
"Not Harry! Anyone but Harry!" he heard in his mind, and then blackness swallowed him.