Remus attempted to convey some of his experience the previous night to his fellow Gryffindors the next morning. Peter and James scoffed and dismissed it out of hand, but Sirius was uncharacteristically quiet and thoughtful all through breakfast and Transfiguration. Then, when Remus was packing his bag to set off for Herbology and James and Peter were mobbing around at the front of the class, Sirius tackled him.

'You should be careful of Snape,' he said abruptly.

'What? Why?'

'The people he hangs around with – I know them – well, my family knows them. They're not – good.'

'Not good?'

'They're – well, I've heard they're mixed up with You Know Who.'

'You think Severus is a Death Eater?' Remus exclaimed.

'Yes – no – I don't know. I'm not trying to stop you doing what you want, you know that Re – just, be careful.'

'I will,' said Remus quietly. It was funny how much Sirius had matured since both the Shrieking Shack incident and his acrimonious departure from the Black ancestral home. He had learned to appreciate Sirius much more, though the occasional blankness behind his grey eyes both frightened and touched Remus's ever-tender heart.

It was with Sirius's gentle warning ringing in his ears that Remus trudged off to Astronomy. He quite enjoyed the theory classes, though not nearly as much as the bimonthly stargazing sessions at midnight. Today, however, he wasn't thinking about stars and planets, but about Severus.

He reached the classroom early and went in, only to find Severus sitting there alone, an enchantment of the Lupus constellation floating above his head. Remus blushed slightly.

'Lupin,' Severus said. He waved his wand and the stars vanished.

Remus stood rooted to the spot and they stared at each other speechlessly until Professor Sinistra stalked in.

'There's a sickness that has decimated our class of Ravenclaws,' she said. 'So it is just the two of you today. I thought we should maximise this opportunity – here, Severus, come and sit at the front by Remus -' who had taken his usual seat, 'and we will discuss what we have covered so far this year. And then, perhaps, we will learn some things that are not in your Astronomy NEWT but which I hope you will find interesting.'

There was the momentary social embarrassment as Severus took the seat next to Remus, and then Professor Sinistra began to quiz them on the constellations and planetary movement they had covered that year, as well as the phases of the moon and rare aberrations. The professor knew about Remus's conditions as, indeed, did all the teaching staff, but she wasn't aware of Severus also knowing. An uncomfortable ten minutes followed for Remus, as both Sinistra and Severus pretended they didn't know how unpleasant it was for him to discuss the waxing and weaning of the moon.

He was extremely glad, therefore, when Professor Sinistra shut Studies of the Heavens by Patrick Copernicus, but his relief didn't last long.

'I am going to teach you,' announced Sinistra, 'how to conjure constellations. I suppose strictly speaking this is a charm, and a difficult charm, but you need to have an intimate knowledge of the constellation and consequently, this is not part of your NEWT syllabus.

'Do either of you know how to cast this spell?'

Both boys were silent. Remus looked quizzically at Severus. Usually the Slytherin enjoyed the chance to show up a Gryffindor.

'Well, the incantation is Mirabilis Stella, but the difficulty lies in both the wand action and the mental image required. You see, the wand action varies from constellation to constellation. Even that, however, is not the greatest challenge. That lies in the picture in your head you must concentrate on.

'To make the charm work, you must associate the constellation with something personal. For example, with the unicorn, you must have a peaceful, healing, beautiful experience in your mind. If you have ever seen a unicorn, that will answer, but if not, you must dig deeper.'

She gave them a moment and then demonstrated the wand action again, before bidding them one by one to attempt the charm.

Remus, who had been concentrating hard on sitting at the top of the astronomy tower at night, staring at a weaning moon and a thousand bright stars in the crisp winter air, managed to conjure the constellation at the first attempt. Severus, however, seemed to be having some difficulty. He had the wand action and incantation mastered, and so Remus realised he must have been struggling with the beautiful mental image necessary. The thought made him suddenly terribly sad.

Professor Sinistra must have realised this, because she gazed at Severus with something like pity in her brown eyes before suggesting another constellation.

'Do either of you boys have a preference?' she asked.

Severus was silent.

'Yes,' Remus blurted out. 'The Lupus.'

Sinistra started and looked at him narrowly, but suspecting nothing from her most attentive student, acquiesced.

Severus was staring at Remus; he could feel those black eyes boring into his profile but he didn't dare turn to meet the gaze.

'You might imagine that for this constellation you would have to imagine fear,' Sinistra said, 'but actually, you need to remember an experience with someone towards whom you feel loyal and protective and kind, someone who you want to save from harm. In essence, you must become the wolf. I warn you, though, that this is a particularly tricky one.'

Remus was barely listening; he was still digesting this surprising information.

'Severus, you first,' said the teacher.

She, though not Remus, was taken aback to see Severus master this after his failure with the unicorn on his first attempt. Remus, in the midst of his confused thoughts, noted one thing about Severus's star-wolf. Its eyes were almost orange – browny-orange…

Remus made a token, half-hearted effort to conjure the charm. After one failure, he pulled himself together.

Now, who would I most like to look after and keep safe from harm… he thought desperately. James, Sirius, Peter… no, they could all look after each other. But what about… yes…

He let the wolf take him over… an image, crystal-clear, of Severus in his mind, being taunted by the other Marauders, and Remus conjured a bright, beautiful Lupus.

'Well done, both of you!' cried the professor. 'I wasn't expecting either of you to manage that – certainly not so fast. Ten points each, and now I think it's time to finish. Hopefully next week the Ravenclaws will have recovered and we can move onto galaxies.'

With that, she swept briskly from the room. Severus was about to follow him, when he was stopped by a hesitant Remus,

'How did you learn to do those constellation things?' Remus asked.

'I only really learnt one: Lupus. I wanted a challenge. I was reading a practical Astronomy book one day and happened to stumble across the spell.'

'What were you thinking of? When you conjured it, I mean.'

'Lupin, would you tell me that? No? Well then…'

And he was gone in the familiar swish of robes.

Remus was left alone, pondering the last. No, he certainly wouldn't have told Severus that he was thinking of him. But surely Severus was thinking of something like a younger brother or sister, maybe… did he even have siblings? He was so very mysterious, and that brusque way of his…

But Remus was a perceptive boy, and he knew that brusqueness was not always due to rudeness. And for all Severus's brusqueness, he didn't feel that the boy disliked him the way he did the other Marauders.

The wizarding world has named some of the stars and constellations differently to the muggle world… luckily for me. Hurray for poetic license!