In the convent, Sam was stalking forward deliberately. He knew somewhere deep inside that he didn't want to do this, but it was like he had no control over his actions at the time. Lilith smirked as she raised her hand, making the door between them slam shut. Sam entered the sanctuary and flung out a hand, making Lilith fly across the room, slamming into the altar and falling to the ground. Sam, with Ruby behind him, advanced toward Lilith and flung out his hand again.
Lilith was forced back against the altar just as Dean came around the corner, seeing what was happening inside the sanctuary, and started running forward just as Ruby looked back at him and smiled, putting out a hand and making the doors of the sanctuary close. Sam not seeing any of it, walked toward Lilith.
"I've been waiting for this...for a very long time," he said, his need for revenge taking him over, making Lilith smirk.
"Then give me your best shot," Lilith goaded, making Sam reach toward her, throwing his power toward her, making a white light shine as Lilith cried out in pain. Sam lowered his hand, the light faded, and the heartbeat slowed. Sam turned toward the door as he heard Dean's voice.
"Sam!" as he started pounding on the bolted door. "Sam!" he said again, banging on the door even harder. Sam felt like he was in a fog. He could barely hear anything that made sense. The sound of a heartbeat took over almost all other sounds. His brother's voice and the pounding and banging sounded distant and faint, but he turned in confusion anyway.
"Dean?" he said mostly to himself. He was sure his brother hated him. Sam heard Ruby beside him but she was even more faint than Dean's voice.
"What are you waiting for?! Now! Sam, now!" Ruby cried as Lilith started laughing coldly with a faint mocking sound.
"You turned yourself into a freak. A monster. And now you're not gonna bite? I'm sorry, but that is honestly adorable," she goaded Sam as the heartbeat quickened, making Sam face her and raised his hand again. He didn't know it, but his eyes turned black as a demon as he concentrated his power. But before he could do anything, a young woman appeared in front of them and kicked Sam away, and she threw a dagger that could kill demons at Ruby, straight through her throat, killing her instantly.
"Sam! What in the hell did you think you were doing?! If you kill this hell bitch, Lucifer goes free!" she screamed as she punched him so hard, his head hit the doors. Sam didn't recognize her, as neither he nor Dean had seen her since she was sixteen. Before he could do anything, she held out her hand, and a soft golden glow entered his body and expelled all of the demon's blood.
"Do not do anything like this again, Samual Winchester," she said in his ear and disappeared as the doors opened with Dean and Castiel entering the room. They saw Sam passed out and Lilith looking defeated as she limply hung her head. Dean got another shock when he saw Ruby dead.
"Bells," Dean heard from Sam's mouth, and he looked around the room for the young woman he viewed as a sister.
"Bella was here?" he asked as he knelt beside his brother sitting him up. "She was. The angels, the ones who didn't want the seal opened, located the one woman who could stop Sam. She's his moral compass. Angels couldn't enter the sanctuary, but we could zap Bella into the room. She's the only one who could get through to him. She was born for Sam," Castiel explained. "We gave her the needed power to pull the demon blood out of Sam. Do not worry. Bella is back to normal and back with her father," Castiel explained, seeing the worry in Dean for Bella. Worried about what the kind of power could do to such a wonderful woman as Bella. The only reason why they found Bella was because she had left her home, and was visiting her father. Bella was smart. If she didn't want to be found, she wouldn't be.
Her home, which she had built herself, was protected against angels and demons alike. Anything else would probably be able to find her, but she was protected from them and demons. Bella took her safety seriously. And what Castiel didn't tell Dean was that Bella was the most selfless human being of all time. She was to be the balance needed to restore good and evil. There was a reason why the Winchesters only worked the cases that brought attention to the supernatural world. For there to be good, there needed to be evil and vice versa. Bella understood that more than anything. Better than what the Winchesters did, that, for sure.
Castiel zapped them away from the sanctuary after they drew protective symbols from demons and angels around the room and on the door. No one would get through unless they were determined. But not many were powerful enough to kill Lilith.