Some time ago mum thumped one of the cats, Tippi, for no real reason. It shocked all of us, because the cats have never been hit before, and this was no gentle tap, it was a heavy audible blow across the back that made the cat cry out.

Mum's new aggressiveness had also been turned against our father, and it embarrasses him as much as it worries him. It can take only a few exchanges for her temper to boil over, and dad just doesn't see it coming. In a roundabout way he told me one day that he was worried about being hit in the face. He was clearly reluctant to talk about it, but said he was afraid in case one of his lenses got smashed and pieces went into his eye. I reassured him that this didn't happen, that lenses pop out and usually fall to the floor, but I couldn't quite believe that mum could threaten him like this.

'It's not very good to be 84 years old and worried about being hit in the face, dad,' I prompted.
'Well, your mum gets so upset about things these days,' was all he said.

Then one day I saw it developing from nothing. Mum went out to collect the mail and came back with three letters, all addressed to dad. He and I were in his bedroom, and I was fixing something on his computer. Mum came in to join us and sat beside dad on the bed - she was quite calm at this point. Dad noticed that the letters were for him and reached for them. Mum snatched them away, and clutched them to her chest. Dad then tried to reason with her, but she was offended, I guess, that he had presumed to take them from her without asking or waiting to be given them. He kept protesting that they were his letters and that if he had hers he would give them to her. He often tries these perfectly reasonable arguments on mum, but all they do is make her feel he is putting her in the wrong. She couldn't argue back, the words just didn't come, and so her frustration steadily mounted to boiling point - and all along dad was completely unaware that this was happening. They both got to their feet and mum, who is now about a foot shorter than dad, started trying to slap his face with the letters. Dad was doing slow-motion karate blocks he'd learnt 40 years ago. It would have been quite comical in another setting.

Dad seemed incapable of doing what he needed to do - drop the subject, let mum have the last word, and simply retrieve the letters when she had forgotten about them. I had to intervene. I told (I did not ask) dad to stay in his room and said I would sort it out with mum. I coaxed mum away into the lounge and sat her down in her armchair. She was still holding the letters tightly. She was tense, but also had a certain air of exultation about her, as if she had just been victorious. Casually, as if I had only just noticed them, I said 'would you like me to look after those, mum?' She looked at me a little suspiciously.

'We won't let him see them, will we?' I said in a stage whisper, jerking my head back towards my dad's bedroom.
'No,' she said with a conspiratorial smirk. Sometimes I sense a little powergame is being played. It is completely one-sided, since dad doesn't even see that there is a power dimension to their relationship.

I sat with mum for a few more minutes and then slipped the letters into my backpack. Some time later I passed them to dad. I tried to tell him that he must go into another room and keep quiet when mum gets like this, but it is hopeless, really; he can't do anything other than what he does.