Parts in italic from chapter 30 in “Deathly Hallows”.
There were so many stars in the sky that night that Snape could not count them all. Usually it helped to fall asleep faster, but not that night. Snape was used to doing everything perfect and he was not able to fall asleep before they were all counted. In his anger he had lost the cont and he started again from the bottom right corner. However, as he counted the first twenty, he was lost in thoughts again. He remembered Sarah. Since she was gone he was sleeping in the Headmaster’s quarters were the ceiling was bewitched similarly as in the Great Hall. He found it easier to look at the sky and see the clouds moving or stars in the bright night like this than looking at the empty place beside him where some month ago Sarah had lain.
She had not returned and he cursed himself for letting her go that night. It had all happened so suddenly that he did not take it for real. He had thought that she would return; he just was not able to accept the thought that she could have left him. When he had recollected form shock he had rushed after her, but it was no use. She was under the Invisibility Cloak so he would not be able to spot her even if she had not gotten far. After running through the gates into the Hogsmeade and checking each place that was open at night he concluded that she had left and he had no idea where to look for her. Snape had returned to his quarters immediately after that to think of what he would say if she came back. He had to come up with a proper apology to get her back. All night he spent sitting besides the fireplace and staring at her engagement ring. Nevertheless, he did not come up with anything sufficient. He knew that he was guilty and that nothing could live down what he had done. Snape still was not sure how it had happened. He had been very cautious about mentioning Lily, because he knew that Sarah was annoyed by it, but at that moment he had lost control. Lily was his love of life after all, and he could not keep it all inside him. Still, he regretted it very much. He had become used to being not alone; he missed Sarah’s company dearly.
During the next day he rushed to his quarters every thirty minutes to check if Sarah had not come back, but all the times he had to come back to the work being anxious whether she would come back at all. After a week all his hopes disappeared. She had nowhere to go in England. There was no way that she could still be somewhere near. He had hoped that she would come back, because he knew that she did not want to go back to States. She had hated the thought about going back, but he had forced her into doing so. After a week of waiting he had taken a grip of himself and written her a letter; however, the owl never came back. The most probable explanation was that she was truly back to her country and the poor owl had not been able to make the way across the ocean. It meant only one thing; Snape would never have a chance to see her again. He did not even consider going to Sates. It was self-evident that he would not be able to find her there. She had never mentioned where exactly she was from. It was still too painful for her to talk about her childhood back home or her parents, and he had never forced her.
Not much had happened since she had gone away. He had spent all the time between Hogwarts and the Malfoy Manor. Working hard on Dubledore’s portrait’s and Voldemort’s orders. The most of his time was used by keeping an eye on the Carrows and delivering the latest news about Potters actions to Dumbledore’s portrait. The only time he had went away it was to the Forest of Dean. Dumbledore had asked him to deliver the Gryffindor’s Sword to Harry. Snape came up with a pretty good idea. His Patronus was an ideal choice, because no one could recognise it. For all of his life he had to hidden his Patronus from everyone so that no one would wonder about its form. It was easy to picture his Patronus as a snake, bat, or something as dark and scary, but anyone who would see a lovely doe with big and expressive eyes would be amazed and unnecessary questions would arise. He had been successful and Dumbledore was still proud of him, but it did not matter to Snape.
It was sometimes hard for Snape to choose whether to dwell about Sarah or Lily. He had found that it was still easier to think about Lily, because he had became used to that over the years. Snape hoped that Sarah was happy. She had been right. He would not be able to give her what she wanted. He found himself too old to think about having children. It would be better for her to find a man of her age with not so tough past as he had no matter how much this though hurt him. It would have been a lot different with Lily though. He had been young back then, full of energy and ready to do whatever she wanted. Potter could not have been a better husband than Snape would have been. Snape still did not believe it.
Snape forgot that he had to count the stars to fall asleep and continued thinking about Lily instead when he was interrupted by a sudden pain in his left arm. The Dark Mark burned and he got a message from Alecto which said that there was an intruder in the castle which was most probably Harry Potter. These were highly important and troubling news. Snape was up immediately and quickly dressed into his usual back robes. Dumbledore had warned Snape long ago that Harry would definitely show up. Actually, Snape had been waiting for him already, because he had finally gotten out of the woods and began some action. Snape had to make sure that he would be safe in Hogwarts and also deliver Dumbledore’s message to him. It was the time. Like Dumbledore had said, Voldemort was protecting his snake. It was put in a protective magical shell just after Potter had escaped the Malfoy Manor and Voldemort was always keeping an eye on it. Fearing for anyone’s life, especially a snake’s, was not characteristic for Voldemort so it was something very important. Snape had to be fast and precise. He could not let Alecto find Potter first, because then everything would be ruined. Most likely Snape would have to abandon his cover and help Potter, but he would never want to do that. Not because all Death Eaters would want to kill him, but because of helping Harry. It was not something Snape would like to do even in the most desperate case. He did not want Harry to know his past and the reason behind his actions so he hoped that he would be there in time.
He ran through the Headmaster’s office turning the attention of all portraits to himself and ran out in the corridor. He was on his way to the Ravenclaw Common Room, where the intruder had been as Alecto had informed him, when he heard footsteps one floor beneath him. He quickly ran there trying to be as quite as he could and quickly caught up with Minerva who was not as quick as he was, because of her age. He was not sure yet whether she was alone or not so he followed her; however suddenly she raised her wand and asked, “Who’s there?”
“It is I,” Snape answered and came out of his hiding place which was behind a suit of armor. He raised his wand to be equal with Minerva and asked the question that was troubling him, “Where are the Carrows?”
“Wherever you told them to be, I expect, Severus,” she answered trying to insult him, but he had gotten used to that during the year.
He carefully looked around trying to spot something in the dark, but he was not surprised to see no one around, because had not forgotten that Potter had a very good Invisibility Cloak. He still thought that Potter was there, because there were clues suggesting to it. First, it was not McGonagall’s night for patrolling the corridors and second, she looked unusually nervous. Snape looked into her eyes.
“Have you seen Harry Potter, Minerva? Because if you have, I must insist—”
Snape was not able to finish the sentence because she suddenly attacked him and with a force which Snape had not expected from her. He quickly cast a Shield Charm and McGonagall’s own spells blast her off her feet. Snape was lucky not to get hit by it. Now it was obvious that Potter was indeed some steps away from him hiding under his cloak. There was no other explanation to her actions. If she would have wanted to do something to Snape she could have done it earlier. There had been a lot of opportunities, but she had taken action at the moment when he had mentioned Potter. Snape was in trouble now. He did not want to hurt Minerva, but in the same time it was essential for him to get her out of the way so that he could get to Potter and deliver Dumbledore’s message to him. Snape did not have time to plan his action, because a lasso of fire flew towards him, which he uickly transformed into a big black snake. After that Snape was forced to hide behind the suit of armor again not to get slashed by daggers that flew at him. Snape saw that she was determined to protect Harry by all means. It’s a shame that she did not know that Snape had the same goal. Snape had not recollected from McGonagall’s attack yet when Flitwick, Sprout and Slughorn joined her. They were all probably sure that Snape was the one who started the fight. He understood that there was no chance for him to win against four skilled professors so he made the only reasonable decision; he ran away. He did not want any victims in this meaningless fight so it was the only thing he could do. He was quick enough to jump out of the window before others caught up. As he flew through the darkness he heard Minerva calling him a coward. If only she knew the truth! Snape was sure that she will never find out what he had intended to do and that he was not a coward. Snape was totally destroyed. Not only he had failed one of the most important missions, but he was also called a coward. It was the word he could not stand. He had never deserved to be called a coward, but he was called so for the second time and it was all because of Potter.