The emergency horn blew three times. Once meant a dragon attack. Twice meant an unknown enemy. Three times meant... "Outcast raid! Valka, come on! Let's go kick some Outcast butt!" (Yes, I realize that Older Stoick wouldn't say that, but I image Younger Stoick acting a bit more like Spitelout and Snotlout) Valka hesitated. "But Stoick, what about Hiccup?" Stoick paused, then shook his head. "He'll be fine. The house is in the middle of the village, so it's well defended. Hiccup will be safe."
Valka nodded, ready for battle. "I've got my sword! Let's go!"
With that the two new parents left their small child in the house. Just like Alvin planned. Savage grinned. This would be fun.
---
Stoick and Valka strode into the house and back up the stairs, chattering about their victory. They walked into Hiccup's room, where Valka went to pick up her son. Hiccup wasn't there. Instead, there was a note. It read: Chief Stoick the Vast of Berk, I have kidnapped your son in the name of Alvin the Treacherous. If you attack Outcast Island, he will pay the price.
Valka began crying as she read the note to Stoick. "It's all my fault. If I had listened to you, if we had made sure Hiccup was guarded and safe, maybe-" Valka scowled and interrupted her husband. "No. Alvin probably sent more than one man. Hiccup would have been taken anyway. No, this is Alvin's fault. He'll pay. By Odin, if I have to wait a hundred years, Alvin will pay for taking our son."
---
The first two months, Alvin attempted to brainwash baby Hiccup into thinking Alvin was his father. That didn't work. Alvin was terrible with children, and he saw too much of Stoick and Valka in Hiccup to get far. He hated the child. So, Alvin then turned Hiccup over to a cruel old woman. The woman didn't have a name, and was horrible, but she knew how to keep a child alive. Once Hiccup was old enough to walk, he would become Alvin's personal slave. Oh, this was going to be fun.