Winterfell was a quiet place in the summer years, which is why Lord Eddard Stark was confused when he awoke to the sounds of commotion in the halls outside his suite. Catelyn was still nestled at his side in their bed, and he did his best not to disturb her as he slipped out from under the sheets and hurriedly dressed before exiting the room. The guards to his quarters were standing at full alert as Rodrik Cassel, the Master-at-Arms, approached with the head of servants, who was consoling a crying maid girl.
"Lord Stark," Cassel rumbled, "I bring fell news."
"Speak, Rodrik," Lord Stark urged.
Cassel bowed his head, and Ned Stark immediately dreaded what he was about to hear. "There was a fault in our guards, m'Lord. Someone breached the castle, poisoned a maid, and stole Lady Arya from her crib. We have searched the grounds…"
Ned missed anything else Cassel said as his words echoed in his mind. Arya was stolen. His baby girl…
"We must search," he rasped out, interrupting Cassel abruptly. "Send out ravens to every major house in the North and Riverlands… notify Kings Landing as well-"
"M'Lord," the head servant spoke up, stopping him in his tracks. "Maester Cressen examined my serving girl that was poisoned; he said the herb came from Essos."
Ned stared in horror at the sturdy woman for several long moments, thoughts of the Slaver's Bay creeping to the surface of this nightmare. "Send a rider to White Harbor," he finally ordered quietly. "Alert the Crown and every major house in the realm. My daughter must be found." Catelyn… "I will join you in my solar shortly. I must inform my wife first."
Catelyn Stark's mournful cries could be heard throughout Winterfell as a rider raced out of the gates and turned east to the coast.
Rarely had the Seven Kingdoms been united behind a common cause in written memory, but the kidnapping of a noble child, especially of a Great House, was enough to push the realm together. While it had been the young Arya Stark from the North who had gone missing, there was the underlying thought that it could be any family next time. The Crown offered 10,000 gold dragons to anyone who brought Arya Stark home and put an equal bounty on her kidnapper's head.
The North was raging with barely concealed fury at the theft of their Warden's child. A harbor watch was formed and began checking every foreign boat that entered White Harbor (and of course to the North, "foreign" included southern ships as well).
Tensions rose as throughout the country, the story of Essosian poison being used in the kidnapping sparked violence towards any who spoke with the flat eastern accent. Anything associated with Essos was quickly socially forbidden; a mob of the Faith Militant set upon a small gathering of worshipers of the Red God, nobles began to favor fabrics from Dorne over those from Mereen, wines and spices from Westeros were now favored over ones from Essos.
While the shift in the common habits of the Seven Kingdoms occurred, the Starks mourned. Lady Stark wandered the halls of Winterfell cloaked in black, typically with one or both of her remaining children by her side. Robb and Sansa may have still been young, but even they knew something grave had happened and grew slightly subdued in their play. If possible, Lord Stark became quieter than before. He recorded any whispered rumor he heard about Arya in a journal in his solar as men reported back from all over the known world.
For three years, he met with sailors and lords and merchants from all corners of Westeros (and Essos, as some saw the share of information as ways to get back into the North's good graces for importing). For those three years, as nothing concrete was unearthed, the rest of Westeros gave up their search. To them, Arya Stark was maybe dead, but certainly lost forever.
It was often said that the Northerners were a stubborn folk, and the search for Arya Stark proved how true that was. While the rest of the kingdom gave up, the North sent a scout to a different part of Essos every three months.
Every three months… even as Catelyn Stark grew pregnant with child again (and again), every three months, the Lord and Lady Stark waited to hear back from their scouts with a tiny flame of hope lingering in their hearts. Their family may have continued to grow, but a piece was always missing.