At the pharmacy, she made me buy a red lipstick, a colour I had thought I couldn’t wear, but she chose one which flattered me. I hadn’t realised there were so many kinds of red. I looked totally different, my mouth now the focal point in my face, whereas I’d always focused on my eyes. Under her direction, I was getting more confident. It was like having a big sister.

We returned to the flat in time for lunch, chattering away, and I could immediately see how happy Jean Louis was that we were getting on, and that Corinne seemed relaxed. We all had lunch together – three kinds of cheese that we had bought, and carottes râpées – and Arthur did his funny face again and we laughed until our sides hurt.

‘Arrête! Arthur! Ça suffit!’ pleaded Corinne, wiping tears from her cheeks.

I got up to clear the plates away and Jean Louis touched me on the arm, giving me a smile of appreciation, which I knew was more for boosting Corinne’s mood than my waitress service. The atmosphere in the house was as frothy as whipped cream and my heart felt full of the joy and anticipation you get on a spring day, when the sun kisses your face for the first time since winter.

When I went to my bedroom to figure out what to wear that evening for my dinner with Olivier, Corinne knocked on my door and put her head around it. ‘Je peux vous aider choisir?’

I had told her I had a date, and she seemed excited by the prospect. I was grateful for her offer, for I was unsure quite what look to go for. Part of me knew Olivier wouldn’t care what I wore, but getting ready for a date is a particular torture you have to put yourself through.

We ended up choosing the lace shirt with black trousers, my Hermès scarf wound tight around my throat. Corinne surveyed me.

‘Attends,’ she said, leaving the room and coming back with a pair of scissors. She pointed to my hair. ‘Je peux?’

I was slightly alarmed. She seemed to want to cut it. My hair was long and dark and straight, all the same length, and I have to say it was one thing that never let me down: it was shiny and behaved itself and I could always rely on it. But Corinne seemed to have a vision, and for some reason I trusted her judgement.

‘Oui,’ I agreed.

She pulled strands of my hair forward and began to cut. Five minutes later, I had a fringe. I stared in the mirror, unable to believe the difference it made. It framed my face perfectly. I looked sophisticated and mysterious. And, with the red lipstick, undeniably chic.

‘Pas mal,’ Corinne said with typical understatement, nodding, then she steered me out to the living room for Jean Louis’ approval. ‘Pas mal, eh?’

He looked at me. It was almost as if he didn’t recognise me. I felt awkward, as if he didn’t approve, but then he smiled.

‘Fantastique!’ he said finally. ‘Comme Jane Birkin, non?’

I shook my head. I hadn’t a clue who Jane Birkin was, but Corinne flipped open a coffee-table book and showed me a photo of a young woman with a fringe and long dark hair and a gap between her teeth, like mine. She looked far more glamorous than me, but if they wanted to make that comparison, it gave me even more confidence.

‘Merci,’ I said to them both, beaming, then reached out to Corinne. ‘Merci.’

This time, she let me hug her, though she flinched slightly as I put my arms round her. She wasn’t great at physical contact. But I was on cloud nine. I was confident about how I looked for the first time in my life. I was excited about my dinner with Olivier. And I was helping to make this a happy house. I was so proud that I’d had the courage to come here. Life really was about taking risks.

As I was starting to realise was the norm in this house, the atmosphere changed for no apparent reason. Clouds gathered and chased away the sunshine we had all basked in over lunch. I had no idea what set Corinne off, but I knew by now that it didn’t take much. She could be as happy as anything, then something would unsettle her, and a blackness would descend. She either became sullen and moody, filling the house and everyone in it with tension, or would fly into one of her tantrums. It was hard to know which was worse. The moods carried on for longer, with everyone waiting for an explosion that sometimes didn’t come. The explosions were shocking: she could rant without taking breath for at least five minutes, and there were often tears too. I wasn’t sure how to handle it, for I came from a household that didn’t indulge in emotional outbursts, but I noticed how desperate Jean Louis was to reassure her, soothing her as if she was one of his children, trying his best to calm her.

Usually, I couldn’t understand half of what she was shouting about. Tonight, I understood very clearly. As I came into the kitchen to see what the commotion was, she was pointing at Arthur, shouting at Jean Louis that it was him who had wanted another baby, not her.

Jean Louis went white. Corinne began to sob. I think she had even shocked herself, and she was heading into hysteria, possibly as a distraction from the awful thing she had said.

‘Charlotte. Hugo.’ I scooped up Arthur, held out my hands and took the three of them off into Hugo’s room, even though I wasn’t supposed to be working. It was only just before seven. I could afford a little time – I wasn’t meeting Olivier until eight.

I picked up one of the Babar books. The stories about the little elephant and his family had quickly become my favourite, and as I read his next adventure to them with Arthur on my lap, I wondered if he had been named after Babar’s cousin. I loved the children’s names too – Pom, Flora, Alexander and Isabelle. I tucked them away for future reference.

I couldn’t think about what Corinne had just said. I was glad Arthur was far too young to understand, and I hoped that the others were too. They were both sitting very close to me. In the other room, I could hear Jean Louis, his tone reassuring as he dealt with Corinne, and eventually I heard them walk down the corridor to their bedroom. I kept looking at my watch. I couldn’t leave the little ones until they were settled, or until Jean Louis came back.

‘Let’s give Arthur his bath,’ I said to Charlotte and Hugo, and they leapt at the suggestion. All they wanted was calm and normality.

We all squished into the bathroom, lined up by the side of the bath while Arthur sat like a little king gazing at us benevolently through steam that smelt of honeysuckle. They piled his bath bubbles on top of his head, and soon there were peals of laughter from all three of them, which lifted my heart. I hoped Corinne could hear them. I hoped it lifted her heart too. I was very worried about her. I didn’t think she could help her behaviour. There was something wrong. She wasn’t a bad person. I’d seen the good side of her. But something was bringing out the worst in her.

I dried Arthur and tucked him into his night things, and the three of us put him to bed, Charlotte carefully winding up the musical mobile which played ‘Au Clair de la Lune’. The slightly wobbly plink of the notes always seemed to soothe him. We said goodnight and crept out of his room, just as Jean Louis came out of the master bedroom. He held out his arms and Hugo and Charlotte ran to his side.

‘Maman was very tired. She is going to sleep now,’ he told them, and they seemed reassured. He looked at me. ‘Thank you so much,’ he said. ‘I think this week has been tough. She needs to rest.’

I hesitated. I was unsure about leaving them all, but Jean Louis pointed to the door.

‘Go. Or you’ll be late. We’ll be fine.’

I didn’t need telling twice.