I'm not exactly sure when this is set but it's sometime between chapter 2 and chapter 32 in the Deathly Hallows.

Disclaimer: I do not own the genius that is Harry Potter, it belong to JK Rowling.

Severus Snape was a cold, nasty, bad-tempered man, and everyone knew it. To most it never seemed like he had a heart, or capable of any emotion other than hate and spite, and for the most part, that was true.

After all the taunts, insults, hexes and pranks the Marauders pulled on him, plus his messed up family life, you can hardly think that Severus Snape would be a ball full of sunshine.

But it doesn't mean he doesn't recognise love when he sees it. Severus Snape loved someone for his whole life, and lost her, so he knew the signs. He knew what it looked like when people loved each other. He'd been one of the only ones to know that it wasn't just the thrill of the chase for Potter, that he really did love Lily Evans (and perhaps that's what hurt the most) and he also knew that through all the insults and detentions she gave him, Lily Evans always knew that if James Potter cleaned up and acted more responsible, it would be all too easy to fall for him.

Yes, it's safe to say (although no one knows it) that Severus Snape did know a little bit when it came to love. Love that just couldn't happen was one type that he was particularly observant of. How could he not be? With all those years loving Lily Evans when he knew that they were too different and that they could never be together.

So when Snape noticed the signs on a particular couple his lips couldn't help but twitch in amusement. After everything Lupin and the rest of the marauders did to him as a teenager, it was nice to get some revenge, even if it was the werewolf that was doing it to himself.

It had all started with the Order meetings and it was Nymphadora who started first. She'd glance at Lupin whenever she knew he wasn't looking. This, at first, made Snape's eyebrow rise into his curtain of greasy black hair but after awhile it all became all too natural. This was when Severus Snape knew it all started.

As the months wore on Severus Snape noticed more. He noticed how the werewolf and Metamorphmagus were always paired together in tasks for the Order, that they would sit together during meetings and talking to each other when there was an opportunity. This increased his suspicions, his lips started to smirk whenever he saw the two together, all too aware that it would happen.

From about January 1995 onwards, at the Order meetings, Snape noticed Lupin glancing at Nymphadora more often, the corners of his lips curled in triumph as he thought of the hurt this would cause one of his childhood enemies (although he would have preferred it be Black, getting Black back for the Whomping Willow incident would have made this revenge all the much sweeter, still, he wasn't complaining).

It was the summer of 1995, after Black's death, that he noticed a bigger change. He noticed Lupin sitting as far away from Nymphadora as he could in meetings, barely talking to her; it was almost as if he was shutting her out of his life. This, of course, made Snape's eyes shine with malice, it was time that one of the marauders felt what he had been feeling for 30 years, to pay them back for everything they did to him. He couldn't be sure, of course, but he was pretty certain the pair had fallen in love, impossible love that Lupin was trying to stop.

And on September the first of 1995, Severus Snape's suspicions were confirmed. When Nymphadora's patronus reached the castle he noticed the shape had changed and knew the animal all too well. It was the shape that he had glimpsed at the end of the tunnel to the Shrieking Shack in his fifth year, it was the shape he had seen as an adult when he was forced to make the Wolfsbane potion for one of the boys that had made his life hell, it was the shape of the werewolf he'd known since he was eleven years old.

And when he went to fetch Potter from the gates he sneered at the woman there, the woman with limp mouse-brown hair and brown eyes, the exact same shade as Lupin's.

Could you blame Severus Snape for sneering at Nymphadora Tonks as he collected his enemy's son from the gates? Could you blame him for loving every minute of realising that someone he despised not be able to be with the person he loved? And you couldn't blame him for smirking at the look on Tonks's face when she realised he knew.

And as he sat in the Malfoy manner, Severus Snape's lips curled with triumph when he heard the Dark Lord taunt the Malfoys by telling them that their niece had married Lupin.

He knew the signs of simply impossible love. He'd been there, done that and Severus Snape felt that someone else should have to suffer. He couldn't choose a more deserving than a boy than one that helped make his life hell.

So as he watched the Death Eaters pound the table in glee at the humiliation of Bellatrix and the Malfoy he just couldn't help but smirk, a smirk that filled his bottomless, cold, black eyes with triumph. It seemed as though all of his childhood enemies had gotten their comeuppance, Potter being dead, Black having to spend 12 years in the hell hole that is Azkaban and then die, Pettigrew being a worthless servant of the Dark Lord, and Lupin had fallen into a trap of impossible love.

And Severus Snape had known. He'd probably been the first to know, before the Lupins themselves and he knew now that the two in question were doomed. They were doomed as all lovers were, to a life of pain and regret. He knew. Severus Snape did.

Author's note: Thank you very much for reading this story. I'd love it if you could review.

This idea just came into my head while re-reading parts of the Half Blood Prince when I stumbled across the part where Snape makes fun of Tonks's Patronus, saying it is weak and I hope you enjoyed it!

Oh and in no way do I share Snape's view on Lupin, in my opinion he was much better than Sirius and James when it came to making fun of Snape but in Snape's view he really did hate them all.

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