
Over half the readers of the Roman Mysteries want Flavia to marry the young orator and poet Gaius Valerius Flaccus, whom Flavia calls Floppy. But who is he? (right: Francesca Isherwood as Flavia, Ben Lloyd-Hughes as Flaccus)
For those who have only seen the TV series - or haven't yet read books 8 to 16 - here are a few excerpts to get you up to speed.
Flavia meets Flaccus
Flavia studied the young man as he came towards them across the moving deck. She remembered seeing him and his slave-boy come on board, but she had been too busy saying goodbye to Scuto and Alma to take much notice.
He was tall and muscular, with dark eyes and floppy dark hair. The two broad stripes on his short-sleeved tunic told Flavia he was a patrician, like Bato. She guessed he was a little younger than her tutor Aristo, about eighteen or nineteen years old. He was very good-looking, so she gave him her prettiest smile.
The young man ignored her smile and went straight up to Bato. 'Hello,' he said in a deep cultured voice. 'My name is Gaius Valerius Flaccus.'
'Marcus Artorius Bato,' said the other. 'Let me introduce you to Flavia Gemina, the captain's daughter, and her friends Jonathan, Nubia and – '
'How long do you think it will take us to reach Corinth?' said the passenger, not even looking at Flavia. He was chewing some kind of gum or resin.
'Four or five days,' said Aristo, stepping up to join them on the crowded platform. 'That's if the wind is favourable. It will take a week to ten days if not.'
Flaccus nodded and moved to the rail. As he did so, he jostled Flavia. She fought back an urge to thump him hard. 'Big oaf,' she muttered under her breath, and gave him a withering look.
But Flaccus was oblivious. He rested his forearms on the polished stern rail and chomped his gum. 'My father left me a nice legacy,' he remarked, 'and I thought I'd see the Seven Sights before I begin to practise law in Rome.'
'Oh, I know the Seven Sights!' cried Flavia, her desire to show off overcoming her irritation. 'They're the famous monuments which everybody says you must see before you die. Some people call them the Seven Wonders of the world.'
'From Delos I plan to go on to Rhodes or Alexandria,' said Flaccus to Bato and Aristo, with barely a glance at Flavia, who had begun to count on her fingers. 'There's the statue of Zeus at Olympia,' she began, 'the Mausoleum at Halicarnassus, the Colossus of – '
'Let's go down to the main deck,' said Flaccus abruptly to Aristo and Bato. 'We can talk more easily there.'
'How rude!' hissed Flavia when the three men had left the stern platform.
Lupus nodded.
'I didn't tell him there would be four children on board,' said Captain Geminus. He glanced over his shoulder at them. 'Flaccus is very rich and he's paying me well, so keep out of his way.'
'Happily,' muttered Flavia and then made her voice deep and cultured: 'My father left me a nice legacy,' she said, mimicking Flaccus and pretending to chomp. 'I thought I'd see the Seven Sights before I become a pompous lawyer up in Rome . . . '
Lupus laughed and Jonathan grinned.
Flavia snorted. 'Look at him, chewing like a cow. And Flaccus is a stupid name. It means big-eared or flabby.'
'Well, he doesn't have big ears and he certainly isn't flabby,' said Jonathan. 'He's got more muscles than most gladiators I know.'
'Then it must refer to his floppy hair.' Flavia clenched her fists to make her biceps big and flipped an imaginary fringe out of her eyes: 'I'm Gaius Vapidius Floppy,' she breathed huskily. 'But you can just call me Floppy.'
(from Roman Mystery VIII, The Colossus of Rhodes)
Flavia gets advice from Flaccus

'Where do you think you're going?' he said, his hand pressing the plaster wall beside her. He looked very handsome in a dark-blue tunic bordered with gold thread.
'To the beach banquet,' she said.
'Looking like that?'
'Looking like what?'
'Looking so grown up. As if you're sixteen years old, with all that dark stuff around your eyes – '
'Thank you,' she said, twirling her parasol. 'It's kohl – '
' – and the colour on your mouth and cheeks… Take it off.'
'What do you mean?'
'Go back to your room and take it off.'
'Who do you think you are?' she cried. 'You're not my pater!'
He leaned closer, his face still grim. 'And if your pater were here? What would he say?'
(from Roman Mystery XI, The Sirens of Surrentum)
Flavia encourages Flaccus

‘The day of the trial!’ breathed Flavia. ‘Do you think it’s an omen?’
‘I hope not,’ he said with a shrug, but she thought she saw him shiver.
‘Drink your wine while it’s hot,’ she said. ‘It will warm you.’
He dutifully took a sip from the steaming beaker.
A breeze from the garden brought a scent of winter jasmine and ruffled his glossy dark hair. Flavia tucked her feet under her and studied him. She always forgot how handsome he was, with his long, thick eyelashes and straight nose and sensitive mouth. She remembered that once she had imagined kissing those lips.
He looked up at her and she felt her cheeks grow warm.
‘Flavia,’ he said. ‘May I tell you something?’
‘Of course,’ she said brightly.
‘Something very personal?’
‘Yes.’ Her heart beat faster.
‘You won't laugh?’
‘I promise.’
He looked down at the scroll. ‘I’m terrified.’
‘Terrified? Of what?’
‘Of the trial.’ His voice was very low.
‘But why?’
‘I've never pleaded a case before.’
‘But you studied rhetoric, didn’t you?’
‘Yes. At the academy in Athens.’
‘And didn’t you say you were going to practise law in Rome?’
‘I’ve been so busy searching for a master criminal that I haven’t had a chance.’
‘Oh. But didn’t you plead cases when you were studying in Athens?’
‘Only practice cases, like the one about Cicero. This is real. Someone’s freedom is at stake. Maybe their life.’ He suddenly seemed very young and vulnerable, and she remembered he was not yet twenty.
‘Oh, Gaius!’ The leather armchair creaked as she sat forward. ‘You’ll be marvellous. You have the most marvellous voice, and you look marvellous in a toga and you know lots of Greek and... you’ll be marvellous!’ She felt herself flushing and wondered if she had gone too far.
‘You repeated the word marvellous too many times,’ he said.
But then he smiled at her, and she knew she had said exactly the right thing.
(from Roman Mystery XIII, The Slave-girl from Jerusalem)
Flavia gets a proposal from Flaccus
‘Flavia,’ he said, his voice deep with emotion. ‘Flavia, will you marry me?’
Flavia closed her mouth.
Flaccus smiled and moved out from behind her father’s desk. ‘We won’t have the betrothal ceremony until June,’ he said, ‘when you come of age. And we don’t have to have the actual wedding until you’re fifteen or sixteen.’ He took another step towards her and now he was so close that she could feel the heat radiating from his muscular body.
‘I just want to know that one day you’ll be mine,’ he said softly, and added, ‘I know you have feelings for me. I can see it in your eyes.’
Flavia’s heart was pounding and she could feel her resolve wavering. Floppy loved her. He loved her!
...From the house next door came the sudden thin cry of a baby...
Flavia swallowed and shook her head. ‘I’m sorry, Gaius Valerius Flaccus,’ she said. ‘But I have just this morning taken a vow of chastity. I made a vow to Diana. Nubia and I have renounced men forever.’
(from Roman Mystery XIV, The Beggar of Volubilis)
Flavia gets a shock
‘Floppy!’ She dropped the hat and ran across the marble floor and threw her arms around him. ‘Oh, Floppy! I can’t believe you’re here!’
For a wonderful moment she was hugging his slim warm waist and smelling his musky cinnamon body oil and hearing his heart thudding against her ear. But instead of greeting her in return, he took her gently by the shoulders and pushed her away. His hands were trembling and his face was very pale. ‘Flavia Gemina,’ he stammered. ‘Is it really you? We all thought you were… That is…’ He gestured stiffly towards two young women standing in the shadows behind him. ‘Flavia, I’d like you to meet Prudentilla. My sponsa.’
(from Roman Mystery XVI, The Prophet from Ephesus)

P.S. Gaius Valerius Flaccus was a real person. Not much is known of him, only that he started an epic poem called the Argonautica in about AD 79 and... but I wouldn't want to spoil anything.
[The 17+ books in the Roman Mysteries series are perfect for children aged 9+, especially those studying Romans as a topic in Key Stage 2 and 3. There are DVDs of some of the books as well as an interactive game.]