Hermione, Harry, and Ron hid and watched their potions professor get slashed and bitten by Voldemort's vile creature. They waited till Voldemort left and came out of hiding. Hermione stood quietly crying as Severus gave Harry his memories. She watched him slump to the side. The trio then ran out the shrieking shack, only Hermione was lagging behind. Neither of the boys noticed so she slinked back to the shack for Severus. She knew something was up. There was no way Professor Severus Snape potions master would allow a simple snake bite and slash to kill him.
Hermione ran back to the room Severus lay in and steeled herself. Severus was surrounded by the blood leaking from his neck wounds. With haste Hermione padded through Severus pockets and found four vials. One after another she poured them down Severus throat, rubbing to force him to swallow. Once all the potions were down she waited for the last of the greenish liquid to seep out of the wounds. One of the vials must have been an antivenin. Satisfied the venom was out she used her wand to cast a spell to knit his wounds together. For now it was all she could do, but his bleeding stopped and she could feel his pulse returning too normal.
Satisfied that he was no longer in mortal danger Hermione remained knelt next to Severus as she apparated them safely into the library at Grimmauld place. For a moment she sat in silence and cast a spell. They were the only two in the house. Quickly she levitated Severus upstairs to the room he used to use. Severus hovered above the bed in his unconsciousness. Quickly, Hermione Scourgified Severus of the spilled blood, dust, and grime then removed his robes, jacket, boots and socks leaving him in his white button up and black slacks. She lowered him back down gently and threw a thick blanket over him that had a warming charm on it. Hermione sat on the floor leaning against the wall watching Severus. She had done her job.
Hermione had always known Severus Snape was on the side of the light. There were plenty of times he could have simply killed Hermione and Ron and taken Harry directly to Voldemort but never did. There were countless things he could have done to help realize Voldemort's cause but he stayed loyal to the light. Even when he killed Albus she knew he was on the side of the light. Somehow she knew something wasn't right but she could never put it into words so therefore never told another soul. But there she sat on the floor content that she had helped the man who'd saved her life countless times. But she was exhausted now and before she knew it she had slumped to her side for a deep sleep on the floor.
Severus had heard the trio leave but a minute or two later heard footsteps coming towards him. Someone had come to make sure he was dead. At least, that's what he thought until he felt hands patting him down then reaching into his jacket pocket for the vials he walked with at all times. He felt soft bony hands pull his mouth open and force the liquid down his throat. Then felt the wounds knit. He hadn't a clue whom this little helper was, but he was thankful. Once getting bit and slashed he quickly realized he did not want death. He felt those same hands grab a bundle of his clothes and felt apparition. He wasn't sure where he was but he felt himself levitating for a while. Then the sensation of scourgify and articles of clothing being removed. Then being placed gently on what he assumed was a mattress and a warming blanket thrown over him. He heard the shuffling of feet and someone sitting on a hard surface. It was then that Severus was able to open his eyes and saw one Hermione Granger passed out on the floor thinner and paler than he had ever seen her and was for the first time since he's known her, thankful.