A Blessed Child, a novel by Linn Ullmann, published in 2008.
On many levels, this is a deep and wonderful novel by a very talented writer. I loved the story, the lyrical and descriptive passages, and I loved the full, round characters. It is set in Sweden and Norway.
And so, the summer days were indistinguishable, as were the summers themselves. Erika and Laura spent most of their time lying in the long grass in front of that house, reading Donald Duck comics and later Starlet, which was really too advanced for them. They ate wild strawberries, staining their hands and mouths red. The sun shone every day, and it was outdoors time, which meant they weren't allowed to go into the house and be a nuisance. Outdoors time was decreed. It was never discussed, had never been explained. Everyone knew what it was. It was unchangeable, like the sun and the moon and the seasons. Outdoors time meant you stayed outside. You didn't go in to get a glass of water or use the toilet, because the pipes would gurgle and Isak would hear. You didn't go to your room to fetch things you'd forgotten to take out with you (like maybe a tennis ball for a game of sevens), because the floorboards would creak. Erika learned all this during her first week on Hammarso. If Isak was disturbed, it broke his concentration and sabotaged his working day. He would storm out of his room, stand in the middle of the kitchen, and bellow. Laura had stories to tell about Isak bellowing, about how scared she'd been, alone with him in the kitchen, about how his face blanched with all that bellowing. First white, then red, then mauve, like a tick ready to pop. Isak would get so angry that saliva dribbled from his mouth.
There was no reason not to believe this. Her mother had warned Erika before she came to Hammarso that Isak could be moody; but her mother didn't call it moody, she called it temperamental. Elisabeh said several times that Erika must not disturb him when he was working, otherwise she risked a flash of his temperamental side - and that wasn't good. Erika would sometimes imagine Isak's temperamental side as a ton of plutonium inside his head. You wouldn't even have to disturb him a lot: annoying him just a little was enough to make the barrel tip over and the plutonium, pale lilac, run out over the floor.