Aisling hidden behind the leaves
Human-Tuatha de Danann(a fairy-like race)
Eriu and Lugh (deceased)
Brendan and Pangur Bán
The Vikings, Crom Cruach
Aisling is a fairy-like creature with magical abilities. She has lived for hundreds of years. She changes forms, but switches primarily between wolf and girl. An unspecified amount of time ago, Crom Cruach killed the rest of her people. Aisling lived alone in the forest surrounding Kells, until Brendan entered the forest in search of ingredients for ink. She watched him from a hidden place, but as Wolves attacked Brendan, she called them back and talked with the boy. She agreed to show him where he could find what he was looking for, but made him promise that he and Pangur Ban, the cat who accompanied him, would never again enter the forest. Aisling led Brendan to the top of a huge old oak tree, where she told him her name. On the way back she lost Brendan accidentally, finding him near Crom Cruach's dwelling. Despite her warnings not to speak his name, Brendan called Crom several times, still believing that he was not real, which resulted in branches of darkness emerging from the open entrance of the cave. Aisling pushed against a statue standing beside the entrance, making it collapse and block the cave.
Later, when Abbot Cellach locked Brendan into his room, Aisling turned Pangur Ban into a spirit-like creature to slip through the keyhole into the tower and free Brendan, which she used a magical song to do. After breaking Brendan out of his room, the pair retreat to the forest where Brendan explains to Aisling why he was locked up. He says that he must retrieve Crom's other eye. A desperate Aisling begs him not to go, saying that Crom will kill him just as he killed her mother and her people. However, Brendan assures Aisling that it is necessary for completing the book, and that without the eye it will be impossible.
The two then go to Crom's cave where Aisling seemingly sacrifices herself so that Brendan can get in, telling him to complete the book and "turn darkness into light." Later, when Brendan returns to where he last saw her, all he finds is his cape and flowers sprouting out of the ground. Aisling was not seen afterwards except in her wolf form, when she saves both Brendan and Brother Aidan from the Vikings.
Years later, she help guides an adult Brendan back to Kells, seemingly happy that he'd returned. She is not seen again for the reminder of the film.
Centuries later, she makes a brief cameo appearance in Song of the Sea, when Ben and Saoirse board a bus full of Trick-O'-Treaters. Aisling could be seen siting on the left side. She doesn't seem to have aged at all since the time of Kells.
Aisling is a fairy-like creature, a member of the now destroyed Tuatha Dé Danann, living in the woods outside of Kells. She is a protector of the forest, and doesn't like unwelcome guests. Her exact age is uncertain, but she is hundreds of years old.
She is very protective of her forest, reacting with hostility to Brendan when they first meet. However, Aisling is also fiercely loyal and supportive once she gets to know and befriend people. She helped Brendan escape his room when his Uncle locked him in for disobeying him, and assisted Brendan in attacking Crom at great peril to herself.
It is also revealed that Aisling can disguise herself into animals such as wolves, deer, and fish. She may be able to become other animals as well, but no evidence of this was shown in the movie. She appears as a salmon in the Origins prequel for Brendan, and appears to be mode-locked to her wolf form by the end of the film. For a short time, however, she appears in her human form when the grown Brendon returns to Kells.
Brendan and Aisling have a very, very strong friendship. At first, Aisling didn't want to even interact with Brendan because he came into her forest uninvited, but they spent more time together and became friends. Aisling helped Brendan escape his room when he was locked inside by his uncle, and helped him enter the cave of Crom. Brendan, for his part, has not been able to effectively balance the scales of assistance, but he is clearly protective of her.
Aisling and Aidan had never interacted. Aisling and his cat are good friends, though.
With Abbot CellachEdit
Aisling and Abbot Cellach had never interacted, thus the fact that Abbot never went outside the walls of Kells.
With Pangur BanEdit
Pangur Ban and Aisling are also friends. Aisling didn't have to do anything to gain Pangur Ban's trust. Aisling also used Pangur Ban to help Brendan escape from his room when Abbot Cellach locked him, and Pangur Ban didn't even hesitate.
"I have lived through many ages, through the eyes of salmon, deer, and wolf. I have seen the Northmen, invading Ireland, destroying all in search of gold. I have seen suffering in the darkness...yet I have seen beauty thrive in the most fragile of places. I have seen the Book, the Book that will turn darkness, into light."
"What're you doing in my forest?"
"You've come to spoil it, haven't you?"
"You were probably sent here by your family, to get food, weren't you?"
"Well, you can go right back where you came from. If you don't, I'll make the wolves get you. Ruurghh!"
"You have no family?"
"No Mother?...I am alone too."
"Not so loud. Go away."
"Yes, but you can't eat those."
"What is ink?" "I don't know what you are talking about, and I don't want to know."
"I will only help you find the things you want, on one condition: you, and your 'pet', must promise, to never come into my forest again."
"C'mon then. I'll ask the forest where they are."
"Wait until you see the rest of my forest."
"Yes, I'm the fastest! Ha, ha, ha!"
"You have climbed a tree before, haven't you?"
"Come on so."
"Saved your life, second time today. I thought you knew how to climb trees."
"Yeah, like bushes!"
"Don't look down. Come on!"
"Look. Aithnionn ciarog ciarog eile."
"Come on. Open your eyes, and I'll tell you my name."
"And this, is my forest."
"I asked them not to sting you. Here's what you're looking for. But they're not really berries. Uggh, they look like boar droppings."
"If you're finished, it's time to go back down."
"A bit left. No, wait! Don't lean on that-- branch."
"We better go now. I know a secret way to get you home."
"What're you doing? Come away!"
"This is a place of suffering!"
"Just come away. It's too dangerous."
"It is the cave of the Dark One."
"He is not imagined. It is waiting in the darkness, waiting for something to awaken it."
"D-don't speak...h-his name..." "I told you, Crom!"
"Brendan? You can visit the forest again, if you like. And Pangur can come too."
"How can I get you out?"
"Why did your uncle put you in there?"
"The Eye of Crom!"
"No Brendan, it's tricking you! You should have stayed in your tower. Crom Cruach took my people. It took my mother. It takes everything. You will die!"
"All right then, I will help you."
"No! I--I must help you."
"Turn the darkness, into...light."
"I have seen the first men land in Ireland, struggling to subdue the land they turned to the Dark One. Their worship gave it strength they could not control."
"I have seen the Tuath De Danann fighting to subdue it."