An owl came fluttering in, perching itself on Draco's shoulder, stretching out its leg.
'Hector! Bringing news from mother, are you?' He carefully unrolled the parchment.

Dear Son,

The time has come for you to show your loyalty to the Dark Lord. If you succeed, your father will soon be out of Azkaban. Bring Costa in the forest next week's Wednesday at 6 pm. Don't be late.

Your mother,

Narcissa Malfoy

Draco was curious – he did want his father to be out of Azkaban, but what did it have to do with Sarah? There was only one way to find out. He made his way to the girls' dormitories and knocked at the door.

'Yes?'

'Costa! I need a word. Now!' he commanded. She opened the door.

'Don't be so polite, I might feel guilty for letting you wait more than 5 seconds,' she said yawning. 'What is it you want, Malfoy?'

'Apologise,' he muttered.

'My! The water has finally begun to flow upwards!' Draco sneered.

'Honestly, I'm sorry about what I said before,' he replied stretching his hand out.

'Oh, that's nothing you should feel sorry about. The only thing you should really apologise for is your birth!'

'If it weren't for father's sake, I'd strangle her!' he thought clenching his fist. 'Costa, get over it. I just want us to be friends.'

'Okay, what is it you want from me? Just tell me and I will do it – but just stop lying.'

'I need you to come to the forest with me, next week Wednesday, at 6,' he said without blushing.

'I will. But you owe me, alright?' she said grinning.

'As long as you're there,' he mumbled, turning around and heading off to his room.

'Hey there, Malfoy!'

'Hey there, Costa! How are you?' Draco asked as she came to stand beside him in front of the forest.

'Stop pretending to be interested in my well-being. Let's just go,' she said walking straight into the woods.

'Don't you even want to know why you're here?' he asked as he caught up with her.

'We'll find that out soon enough, now, won't we?'

After a fifteen minute walk, they heard someone approaching from the opposite side.

They stopped as they saw a hooded figure stepping out of the darkness. For a moment Sarah lost her courage and grabbed Draco's hand. He was far too scared, too, to even think about letting go or turn to look at her.

'Well done, young Malfoy. If we succeed your father will be with you soon. Now, girl, come here. I've heard you were a singularly gifted young witch,' said a cold female voice from underneath the hood.

Sarah quickly restrained herself and stepped forward letting go of Draco's hand.

'What may I do for you?' she said her voice trembling slightly as she struggled for words.

'No need to be scared. I can give you all you want, young girl. All I want is something in return,' the voice hissed.

'You wouldn't bother to tell me what that would be, would you?' she answered a bit braver.

'I need you to brew my master a potion. One he couldn't possibly brew by himself, being neither female nor young. But you must show him true loyalty in order for it to work. I'm talking, of course, about the Elixir of Youth. With that, he will regain the beautiful 16 year-old self, which would be very helpful regarding the fact that most of people don't find his looks very trustworthy,' she said with what sounded like cold, high-pitched laughter.

'Hell, I've read about that potion. It's highly complicated and strictly forbidden. Not that I cared about the latter. But you can brew it yourself, except for my willingly given blood that is. How did he know I was still a virgin?'

Draco watched the whole scene and got even more confused with every word Sarah said.

'Ah, so you are even cleverer than I have been told you were. Let's say, he has his spies. So you will give the blood, then I suppose?' It didn't really sound like a question. 'I only need one cup full, that much you can regain in about a week.'

Sarah nodded and took one more step forward and nodded gravely. Bellatrix (whom else did you expect it to be? ;)) gave her wand a slight wave and a cup appeared on the ground between them.
'Are you ready?' she hissed.

'I am.'

'Very well then.' She waved her wand and blood streamed out of a large cut on Sarah's upper arm dripping directly into the cup.

She winced of pain and after a few minutes the cup was filled. With another wave of Bellatrix' wand the cut was gone and all one could see was a thin scar.

'You dark people tend to leave scars, don't you?' Draco asked from behind Sarah.

The Death Eater took the cup.
'Be here next month's full moon at the same time,' she said and vanished into thin air.

Sarah suddenly felt very dizzy.
'What have I done?' she mumbled under her breath.

Draco stepped beside her and put one arm around her.
'The only right thing to do. Come, I'll take you back. I owe you, right?' he said half smiling.