"Castiel, something's wrong!" You looked over at your angelic brother, panic filling you. Having just been forced to leave Heaven and become human, you were unaccustomed to such severe pain. You clutched your abdomen, shrieking as it felt like someone shoved an angel blade into you. Repeatedly. You gasped in pain and Castiel pressed his foot harder onto the gas pedal of his car. He was weak from fighting in Heaven, and had taken it upon himself to deliver you to the Winchesters to be cared for and taught about being human.
"I'm sorry, (y/n), but I cannot drive any faster. What is wrong?" You groaned, and moaned, "My abdomen, it feels as though it is being stabbed!" Your older brother reached over and placed a hand on your stomach, and frowned.
"What is it, Castiel? What is wrong? Can you heal it?" He shook his head, then you let out a scream as you looked down and saw blood covering your lap. Castiel looked glanced over, his blue eyes widened in horror, and he pulled his car off the road. He touched your forehead and suddenly you were sitting on the floor of the Bunker, blood slowly seeping out of you. He knelt next to you, and looked around frantically, his tan trench-coat brushing your jeans as he spun.
"Sam! Dean!" He yelled for the brothers, his deep voice echoing throughout the vast room. You shrieked as another sharp pain shot through your stomach. Your (e/c) eyes began to fill with fearful tears as Sam ran into the room. He took in the scene in front of him. You, clutching your stomach, collapsed on the floor, blood surrounding you. Cas, terrified, holding you close. He ran over as Dean bolted into the room, a medical kit in hand. They reached you at the same time, and Sam pried your hands away from your stomach, looking for the wound. When he found none, he felt your back, then stopped. He turned to Cas and Dean and said, "We need to go to the store."
Cas gave them a confused look, then comprehension dawned. He nodded, then asked, "Can you handle it if I take you to the store and back?" Dean nodded, and Castiel and him disappeared. You felt tears sliding down your cheeks and angrily cried out, "What is happening to me?" Sam rubbed your back and said, "You're human now, (y/n). That means you get everything that comes with it. Including...." You groaned as you realized what he meant. A period, the cycle human females went through monthly. You had to deal with it now. Suddenly Dean appeared in front of you and tossed a bag at you. "I am never doing that again." You picked up the bag and Cas tapped your shoulder from behind, flying you to the bathroom, then leaving you.
Once you had cleaned up, gotten new clothes, and put on a pad, you returned to the library, a small bottle of pills in hand. "What are the these for?" You suddenly collapsed, pain shooting through your stomach again. Dean huffed and said, "For that. You really have a lot to learn about being human." You quickly shoved two pills in your mouth, swallowing them, and shakily stood. Cas made his way over and gave you a big hug, then said goodbye. He promised he would come visit when he could, and then he was gone, leaving nothing but a warm feeling on your shoulders and the sound of wings. You looked nervously over at Sam and Dean, who were at the table and smiled. They smiled back and Dean said, "Welcome to humanity, (y/n)."