If there was one thing you could say for my father, he never beat his wife.

'He hit her!' Pa was spluttering; he was so eager to tell my wife Helena that her brother was guilty of domestic violence. 'He came right out and admitted it: Camillus Justinus struck Claudia Rufina!'

'I bet he told you that in confidence too,' I snapped. 'So you come bursting in here only five minutes later and tell us!' Justinus must have gone for a bribe to reinstate himself Once Pa had sold the culprit an exorbitant 'forgive me darling' gift, my parent had rushed straight from his fine art warehouse at the Saepta Julia to our house, eager to snitch. 'You' d never catch me behaving like that,' he boasted self-righteously. 'Agreed. Your faults are more insidious.' There were plenty of drunken male bullies in Rome, and plenty of downtrodden wives who refused to leave them, but as I licked the breakfast honey from my fingers and wished he would go away, I was glaring at a much more subtle character. Marcus Didius Favonius, who had renamed himself Geminus for reasons of his own, was about as complicated as they come. Most people called my father a lovable rogue. Most people, therefore, were bemused that I loathed him. 'I never hit your mother in my life!' I may have sounded weary. 'No, you just walked out on her and seven children, leaving Mother to bring us up as best she could.'

'I sent her money.' My father's contributions were a fraction of the fortune he amassed in the course of his dealings as an auctioneer, antique dealer, and reproduction marble salesman.

'If Ma had been given a denarius for every foolish buyer of flaky Greek "original statues" you conned, we would all have dined on peacocks and my sisters would have had dowries to buy tribunes as husbands.'

All right, I admit it: Pa was right when he muttered: 'Giving money to any of your sisters would have been a bad idea.' The point about Pa is that he could, if it was absolutely unavoidable, put up a fight. It would be a fight worth watching, if you had half an hour before your next appointment and a piece of Lucanian sausage to chew on while you stood there. Yet to him, the concept of any husband daring to hit a feisty wife (the only kind my father knew about, since he came from the Aventine where women give no quarter) was about as likely as getting a Vestal Virgin to buy him a drink. He also knew that Quintus Camillus Justinus was the son of a respectable, thoroughly amiable senator; he was my wife's younger brother, in general her favourite; everyone spoke highly of Quintus. Come to that, he had always been my favourite. If you overlooked a few failings – little quirks, like stealing his own brother's bride and backing out of a respectable career so he could run off to North Africa to grow silphium (which is extinct, but that didn't stop him) – he was a nice lad. Helena and I were both very fond of him.

From the moment of their elopement, Claudia and Quintus had had their difficulties. It was the usual story. He had been too young to get married; she was much too keen on the idea. They were in love when they did it. That is more than most couples can say. Now that they had a baby son, we all assumed they would set aside their problems. If they divorced, they would both be expected to marry other people anyway. They could end up with worse. Justinus, who was the real offender in their stormy relationship, would certainly lose out, because the one thing he had acquired with Claudia was joyful access to her very large fortune. She was a fiery piece when she needed to be, and her habit nowadays was to wear her emeralds on every occasion, to remind him of what he would lose (apart from his dear little son Gaius) if they separated.

Helena Justina, my level-headed wife weighed in, making it clear where her sympathies would lie. 'Calm down, Geminus, and tell us what caused poor Quintus to be in this trouble.' She tapped my still excited father on the chest, to soothe him. 'Where is my brother now?'

'Your noble father has requested that the villain leave the family home!' Quintus and Claudia lived with his parents; it cannot have helped. Pa, whose children and grandchildren rejected all forms of supervision, especially from him, seemed impressed by the senator's bravery. He assumed a disapproving air. From the biggest reprobate on the Aventine, this was ludicrous. Pa gazed at me with those tricky brown eyes, running his hands through the wild grey curls that still clustered on his wicked old head. He was daring me to be flippant. I knew when to hold my peace. I wasn't mad.

'So where can he go?' A curious note of hysteria squeaked its way into Helena's voice.

'He told me he has camped out in your uncle's old house.' The senator had inherited this property next door to his own. I knew that house was currently empty. The senator needed the rent, but the last tenants had left suddenly.

'Well, that's convenient.' Helena sounded brisk; she was a practical woman. 'Did my brother say what caused him to lash out at dear Claudia?'

'Apparently,' my father's tone was lugubrious – the old bastard was enjoying every moment of this – 'your brother has an old girlfriend in town.'

'Oh "girlfriend" is putting it far too strongly, Geminus!' I gazed at Helena fondly and let her commit herself: 'I know who you mean of course – Veleda is her name -' All Rome knew the past history of this notorious female – though, so far, few people realised she and Quintus had ever been connected. His wife must have heard something, however. I guessed Quintus himself had stupidly told her. 'Quintus may have met the woman once,' Helena declared, trying to reassure herself, 'but it was a long time ago, long before he was married or had even heard of Claudia – and anything that occurred between them happened very far away!' 'In a forest, I believe!' Pa smirked, as if trees were disgusting. Helena looked hot. 'Veleda is a barbarian, a German from beyond the frontier of the Empire – ' 'Isn't your sister-in-law also from outside Italy?' Pa now produced a leer, his speciality.

'Claudia comes from Hispania Baetica. Absolutely civilised. An utterly different background and position. Spain has been Romanised for generations. Claudia is a Roman citizen, whereas the prophetess – '

'Oh this Veleda is a prophetess?' Pa snorted.

'Not good enough to foresee her own doom!' snapped Helena.

'She has been captured and brought to Rome for execution on the Capitol. Veleda offers no hope of romance to my brother and no threat to his wife. Even Claudia at her most sensitive should be able to see that he can have nothing more to do with this woman. So what in Hades can have driven him to hit her?' A wily look appeared upon Pa's face. People say we are alike physically. This was an expression I had certainly not inherited. 'It could be,' my father speculated (knowing the reason full well, of course), 'because Claudia Rufina hit him first.'