Disclaimer: Everything you know belongs to the genius that is J.K.Rowling.
Lily and Arabella's Hogwarts Life, Chapter 5: Werewolf
Two weeks had passed and a restless Moony (Remus Lupin) walked back and forth, back and forth in the common room. Sometimes he would glance up at the clock, and as it stroked six he left the common room without a word. About five minutes later, Lily left, well hidden under James' invisibility cloak. She hurried out of the castle and spotted Remus and Miss Pomfrit, the school nurse, entering an entrance in the, at the time, unmoving Whomping Willow. She waited for a while and soon saw the nurse leaving the tree and as the woman disappeared through the huge doors of the castle, Lily moved closer to the tree. She found a long stick and carefully prodded it against one of the knots on the tree trunk, immediately the moving tree froze. She dunked in between the roots and found herself in a dark hall. She had to bend down to be able to crawl through it. Eventually she came to the ending and looked out on the inside of the Shrieking Shack. The Shrieking Shack had for the last four years been claimed to be inhabited by awful ghosts, when it was in reality Remus who haunted the shack. Lily moved through the rooms of the shack 'til she found the room where Remus was in. Remus sat on a huge bed in a huge room visibly damaged. Lily sat down next to him on the bed and clasped his arm tightly. He looked at her. "Now will you show me your animagus form?" He asked in a hoarse voice. She hadn't let anyone see her form, but had calmed them by letting them know it was huge enough to stop a werewolf, Arabella had confirmed this, as she knew which form Lily took. She smiled secretively at him and got up and stood on the floor in front of him.
"Ready?" She asked. He nodded. Lily closed her eyes, and with a little 'pop' she turned into--- a White Wolf. She popped back into herself after a minute or so and brought out the deck of cards she had brought.
"Explosive Snap?" she asked. Remus smiled and they settled on the floor with the cards in front of themselves. As it grew closer to moonrise Remus looked worse and worse. As Lily noticed a tinge of red glowing in his eyes, she changed into a wolf again and settled on the bed, watching Remus. It felt like a very long wait, but when it happened, it was quite sudden. Remus suddenly cried out; first he went rigid, then an uncontrollable shaking seized him. Lily felt bad for her friend; he had to go through the same routine every month! Remus' head and body elongated and a dreadful snarling that sounded like a cross between an animal noise and a human scream escaped Remus' mouth. His shoulders hunched and his hands curled into paws with long claws. Standing before her wasn't longer her friend Remus, but a huge wolf with ragged grey coat and glowing red eyes, a slavering mouth with a tong hanging out, a hungry mouth with no food in sight, as the only acceptable food for him this night would be human flesh.
Don't change back, Lily reminded herself. No matter how afraid you are, no matter how much it hurts, don't change back.
Remus paced nervously around on the floor, glancing around in the room, looking for ways of escape. He gnarled at Lily, lying in the bed in shape of a wolf. All Remus' thought was lost. Only the instinct of the blood- and flesh- hunting werewolf was left. Lily jumped of the bed and jogged around in the room, her four paws hitting the floor with regular thuds. She felt, more than saw, the werewolf's eyes on her. Suddenly the werewolf leaped through the air, aiming straight at her. His jaws were open, and his claws extended as he leaped. Lily roared and reared up on her hind legs, her sharp teeth bared and her claws ready to defend herself. Her animal instincts vibrated through her body, she felt it in every single hair on her body as Remus hit her on full force. He knocked her to the ground, ready to bite, but she had been prepared. She sunk her teeth's into his neck, dragging in his scruff. She could feel the blood in her mouth, but didn't let go. She held on and eventually felt the werewolf give up and released him. The werewolf jogged over to the other side of the room and eyed her with red eyes. Lily sat down on the floor and felt her eyes slip, then Remus was at her with full force again. He sunk his teeth into her left thigh and she tossed herself around and clasped her jaws firmly over one of his paws. He growled in pain and let her go, but didn't leave. He attacked her again and pinned her to the floor. But she had been prepared and bushed him of with her hind legs, which had been under him as he had pinned her by lying on top of her. She span him around and by a second she had him pinned on the floor, much in the same position he had pinned her earlier. She stared into his red eyes and saw them glint grey before his earlier so stiff legs relaxed and she let him go. He tussled over to the other side of the room and slipped down the wall 'till he was on his belly, but he still had his eyes fastened on her. He probably felt safer with her, as she was a wolf much like himself. Lily jumped up on the bad again and prodded her head on her paws. As Remus' eyelids started to slip, Lily felt sleep grab hold on her and fell into an easy sleep.
The first thing Lily saw as she awakened was Remus asleep on the floor. His clothes were torn, but he wasn't too bruised , she noted. She jumped down on the floor, still in wolf form, and pushed her wet snout against his shoulder. Remus blinked his eyes and looked up in her huge, yellow eyes. He opened his mouth to scream, but just in time he remembered who she was. He shakily got up on his knees and hugged Lily tightly. Lily transfigured back into Lily again and helped him onto the bed. She noted huge bite-marks on his shoulder and right arm.
"Did—Did I do that?" She asked lightly touching the wound.
"I'm sorry, I didn't men to bite that hard..."
"It's okay, Lils. I would have hurt myself much worse." She looked at him with sorrowful eyes.
"I'm sorry..."
"It's okay." Remus said again.
"You sure?" He nodded.
"You have to go..." He said.
"Miss Pomfrit..." Lily nodded and kissed him on the cheek before she left. In the hall she pulled James' invisibility cloak over herself and lowly walked up to the castle. She entered the portrait hole (haemorrhage) and exhaustingly fell onto a couch after pulling off the invisibility cloak. But instead of the soft pillows you would expect to hit, Lily sat on someone. As she got up again she saw that this someone was James. She shook him awake by the shoulders and seated herself next to him. They sat there in silence 'til Arabella, Sirius and Peter had awakened and went to the Hospital Wing to visit Remus. Remus was in a much better condition, and since there were only one night of full moon, the nurse agreed to let Remus go, that plus the fact that a mass of teenagers had begged her. The Marauders, and Lily and Arabella, captured the best sofa corner in the common room that evening and annoyed all of the seventh years studying for their exams by laughing too often and too loud. As the clock ticked towards one AM Lily's head nodded and eventually fell down at Remus' shoulder. After another half-hour or so, her head was in his lap. Sirius eyed the two.
"You dating, or something?" Remus looked down at the girl lying with her head in his lap.
"Nah. She's a friend--- maybe more like a sister---" Sirius nodded. 'But how does she see it?' He wondered.
The next day Lily introduced Iris to the boys, and she was soon accepted. From that day the group consisted of seven.