Valkyrie Cain had had some pretty strange and disturbing days. She'd seen her friend nailed to a chair, she'd been technically dead for twenty-four hours while a crazed surgeon removed her heart, she'd seen her reflection being shot. But she felt she could safely say without exaggeration that those things paled in comparison to the strangeness and disturbingness of that cold November afternoon.

The irony was that it should have been completely normal and ordinary. She was on her day off, relaxing with her family in the living room. Alice, now sixteen, was at HMV where she worked, but they were expecting her home soon.

'You know, Steph,' her mum remarked, an amused glint in her eyes as she peered at her daughter over her cup of tea, 'I swear you get younger every time I look at you.'

Valkyrie let out an uncomfortable laugh. She was thirty-two by this stage, but still looked eighteen. She and Alice, who actually was eighteen, looked like twins. She frequently caught her parents casting her puzzled glances when they thought she wasn't looking, but this was the first time either of them had ever broached the subject directly.

'Um, lamb embryos,' she responded.

'Lamb embryos?'

'That's my secret. You get them injected into your face and they make you look young again. It's common sense really. Replacing old cells with new ones. Anyone want some more tea?'

Without waiting for them to answer, she picked up the teapot and hurried back into the kitchen without a backward glance, her heart still beating too fast. Relax, she told herself. Crisis averted.

She was refilling the kettle when the doorbell rang. 'I'll get it,' she called to her parents and went to answer the door. She saw who was standing there.

She screamed.

The person standing on her doorstep - or, at least, one of the people standing on her doorstep - screamed too.

Alice wedged her foot in the door before Valkyrie could instinctively slam it. 'What's wrong?' she asked, alarmed.

For Alice was one of the people standing on her doorstep.

'What are you doing here?' Valkyrie croaked, her eyes fixed on the boy standing beside her sister, drinking in his appearance. He stared at her, too, with an expression of utter shock and horror on his face. 'What's going on?'

'Do you two know each other?' Alice demanded.

The boy dragged his eyes away from Valkyrie and replied slowly, 'We have some history.'

'What? That's not possible. You told me you were nineteen. Stephanie is thirty-two. How could you have history?'

'He meant history in the platonic sense,' Valkyrie said quickly. 'Fletcher, what are you doing here?'

Fletcher - yes, it was Fletcher - didn't meet her eyes. 'Val, I really am sorry... I had no idea she was your sister.'

'What are you sorry about?' Alice said. 'I don't get it.'

Valkyrie ignored her. 'It doesn't matter whether you knew or not,' she addressed Fletcher, voice shaking with anger. 'The fact is, you're thirty-four - '

'Wait, what?' said Alice.

' - and you're going around picking up eighteen-year-olds and lying about your age like some kind of creepy paedophile!'

'I still look like a teenager,' Fletcher protested. 'And I swear this doesn't happen on a regular basis, it's just, I met her at HMV a few weeks ago and we were talking and she - she reminded me of you.'

'How are you thirty-four?' Alice repeated, her voice getting higher.

'I'll go now,' said Fletcher, but then they heard voices from behind Valkyrie.

'Stephanie?'

'Alice?'

'Is something wrong?'

Desmond and Melissa emerged from the sitting room and stared at them.

'You look familiar,' Melissa said to Fletcher.

'I remember you!' said Desmond. 'You used to be Stephanie's boyfriend, the one with the demented porcupine hair!'

'Manners, Desmond,' Melissa muttered, then looked more closely at Fletcher. 'Wait, you're right! It is him!'

'Uh, hi,' said Fletcher awkwardly. 'It's great to see you again.'

'You haven't changed at all,' said Melissa.

'No, really,' said Desmond. 'You haven't changed at all. You must be in your thirties by now and yet you still look eighteen. Why is that?'

'Lamb embryos,' said Fletcher. 'Everyone's doing it.'

'I must try that,' Melissa murmured to herself.

'You won't regret it,' Fletcher assured her.

'Can someone please tell me what's going on?' said Alice, reduced to pleading. No-one answered her.

'Look,' said Valkyrie, finally taking control of the situation, 'this is all just a huge misunderstanding. Right, Fletch?'

'Yep,' said Fletcher. 'I was just leaving anyway.'

'Don't you want a cup of tea?' asked Melissa.

'No, he doesn't,' said Valkyrie.

'Well, if you're sure...' said Melissa.

'I am sure,' said Fletcher. 'Bye.' He waved to them all and then practically ran back down the path. When Melissa, Alice and Desmond weren't looking, he turned around and mouthed 'Call me' at Valkyrie, then vanished.

'Well, that was odd,' said Melissa. Alice looked furious.

'What is going on?' Alice hissed at her sister.

'Nothing,' said Valkyrie once her parents were back inside the house and out of earshot. 'Look, I'm sorry about Fletcher. He's a creep. He shouldn't be allowed out on the streets. I was just doing you a favour.'

Alice looked hesitantly at the door. 'But he seemed really nice. And he didn't look thirty-four...'

'LAMB EMBRYOS.'

'... I don't get it. Did you two used to be together or something?'

'A long, long time ago, yeah. But it doesn't even matter any more. Promise me you won't ever speak to him again.'

'All right, then,' said Alice doubtfully.

'Good girl.' Valkyrie smiled, then went up to her room. Alice stood in the hall, pondering.

The next evening, Alice Edgley heard a strange noise in her back garden. She opened the window. A pale, dark haired boy stood there, looking up at her.

'Um,' said Alice. 'Who are you?'

The boy smiled. 'My name is Caelan.'