A/N: This story is just a dumb idea that popped into my mind.
I had to adjust the age of the twins upwards a little bit.
Let me know what you think. Should I continue this?

Everything here seemed to him as if it was part of one of the many stories his nurse had once told him. On the Fingers, everything was bleak and stony and life was simple. The old tower in which he had lived with his father didn't even have a name. But here, everything was different at first sight. Well, there were rocks too - huge ones, to be exact.

Curiously, Petyr let his gaze wander out of the window of the carriage and examined the castle which was located high up on a rock. His father had told him that the castle was impregnable - and that was what it looked like. Like an unfriendly giant stretching out his hands towards him. "Casterly Rock," he mumbled softly to himself and leaned back, sighing. Petyr's nurse lovingly stroked his brown hair.

"You have been granted a great honor, Petyr."

Petyr sighed again. "I know." He wasn't quite sure if he should be happy or sad. On the one hand, there never happened anything exciting on the Fingers, but on the other hand it was his home. His father had stayed on the Fingers and had sent him to his new "family" with nothing more than an old carriage, provisions and a bag full of belongings. The closer they came to Casterly Rock, the more the sound of hustle and bustle and the smell of food filled the air. When he heard the sound of a gate opening, he closed his eyes for a moment.

"We're here, Littlefinger. You can get out." At the words of his nurse, he opened his eyes again. Although he already counted eight namedays, he was quite small for his age. The children of the few servants of his father had reminded him often enough. Sometimes they left it at calling him "Littlefinger" and sometimes they threw pebbles at him when nobody was watching. This nickname had been adopted by the adults at some point, and he was beginning to get used to it. But he didn't get used to the other children on the Fingers. Once, they had pretended that he was allowed to play hide and seek with them. So, while he closed his eyes and counted to ten in a small chamber, they locked him up. Only hours later had a servant found him there.
At least he had escaped that now - unless the children in the Westerlands behaved in the same way. His father had told him a lot about the Lannisters. If one wanted to believe his words, they were proud, rich, generous, strong-willed and cunning people who always paid their debts. Petyr, however, did not believe that. No one could unite so many good things at once. Everyone had weaknesses.
When he got out of the carriage, a pleasant breeze immediately blew towards him. Much warmer than in his homeland. His gaze fell on a middle-aged, dark-haired woman who had placed her hands on the shoulders of two children.

"Jaime, Cersei, welcome Petyr Baelish. The new ward of your father and your new playmate." Cersei and Jaime were a little younger than him, and yet Jaime was already taller than him. "Hello." Jaime nodded at him with a smile and Petyr returned the smile with relief. Maybe it wasn't so bad here. The girl also greeted him by making an elegant curtsey.

"It is a pleasure to meet you." Her hair shone in the sunlight like liquid gold and her eyes like green gems. When he thought about it, she reminded Petyr of a cat. A real lioness. Her twin brother looked like her male counterpart. And Petyr stood there, small and puny in his grey, worn out clothes. "The pleasure is mine.," he replied and nodded to both of them.

"Come with me," the woman spoke again. "My name is Elenya and I will take good care of you from now on. I'll show you your room for now." Petyr nodded obediently and followed the woman into the castle and up the stairs. Compared to his father's tower, this dwelling here was a monster. A spectacular palace in which guards patrolled everywhere, with a golden lion on their chest. Petyr suppressed the urge to wish each of them a good day and went on. In front of a tower room, his companion stopped and opened the door for him. Cersei and Jaime had followed them with some distance. "I hope you like it.," Elenya said to him.

"I helped with the furnishing and decorating," Cersei proudly remarked, pointing to the red room. "Look!" The golden lion was again to be found on the bed linen. Apparently, his new family immediately wanted to make it clear to him where his loyalty should lie from now on. "It is very pretty, mylady. Although I prefer green." Cersei made a face. "Red is much better than green."

"I think green is better, too," Jaime interfered and promptly got a deadly look from Cersei. "That's enough now, children. Let him arrive first." With a warm smile Elenya turned to Petyr again. "Set yourself up a bit and freshen up, then you can go to sleep. It is late. I'll check on you tomorrow morning and wake you up. Then you will also get to know the Lord."

As soon as she had finished speaking, Elenya gently pushed the twins out the door and closed it. Petyr let himself fall backwards onto his bed. It felt much softer than the one he had slept in at home and smelled pleasantly of lavender. As soon as he closed his eyes, he fell asleep from exhaustion without unpacking his bag or undressing. For some reason he dreamed of a green-eyed, gold-tipped cat snuggling up to a mockingbird in a dark dungeon that night.