A/N: This is something that I wrote and reworked for a while. I'm most likely not going to add to this, mainly because I'm not sure how. Let me know what you think.
Stargate and Buffy belong to their respective peoples. This was written for fun and pure speculation.
“Incoming wormhole, Sir. It's SG-1's code," Walter Harriman called out.
“Hello!" Jack called out, as he and the other members of SG-1 walked up to the seated sergeant.
"Open the Iris," General Hammond ordered.
“Yes, sir," Walter acknowledged, placing his palm in the device that controlled the metal shield around the Stargate.
They waited about three minutes until something, or rather someone ran through the Stargate. The girl couldn't be more than ten years old. Her white blonde hair was disheveled, and covered her face as she collapsed on the ramp. Jack and the rest of his team rushed into the Gate room as the General called for a medical team.
Jack reached the girl first. He picked her up and turned her over so he could see her face. Her eyes reminded him of the mossy green that his mother had, but it was what she said when she briefly opened her eyes that made his heart stop. "Daddy?"
Jack didn't leave her bedside since the girl called him daddy. He kept rubbing his face, worry flooding through him. He had never seen this girl before in his life, but she knew who he was, and thought of him as daddy. Waiting for her to wake up had become a torturous event.
The girl stirred three hours after Janet had examined her and treated the many laser blasts that had hit her face, hands, arms, and legs. She opened her eyes, calling out, "Daddy?"
Jack squeezed her hand, which was still in his, and tried to comfort her. "I'm right here, pumpkin, not going anywhere."
Her next question threw him a little bit. "What year is it?"
"2001, why?" Jack asked.
"Mom did it, she managed to change history," The girl whispered to herself.
"I don't understand, you mom did what?" Jack asked, trying not to get angry at a woman that he never knew.
"Mom found out that she couldn't have any more kids, and told the rest of the gang. She then came to us, to convince you to help her. She left, then we had a really long talk about what changing the past might do to the current future.
“Since the whole population of Earth was going to die out in 100 years, you decided that it might be worth the risk. You told me that it was my choice to help out, and that you were going to get me to the gate no matter what. You didn't want what happened to my brother to happen to me, you wanted me to live a long life. So I followed you and Danny and Mom to the Gate terminal and watched as all of you were brought down by the defense system. I ran down to the gate, and took the note that Mom had taken from you and walked through the gate. The next thing I remember is seeing your face." the girl explained.
"Will you tell me your name?" Jack asked.
"My name is Joana Elizabeth Carter O'Neill, though since I started school I've gone by Buffy O'Neill," Buffy answered.
Oh God, Jack thought. She's my daughter. She's Carter's daughter. She's OUR daughter.
Buffy was placed in Jack's on-base quarters for the time being. Jack had the unpleasant task of telling Hammond exactly who and where Buffy had come from and why. He didn't like it one bit.
"Sir, you wanted to see me?" Jack asked as he knocked.
"Come in, Jack. Janet has the results to most of the tests she ran on the girl. You want to tell me when you had a daughter and how she came through the Stargate, and what exactly the note means?" Hammond asked.
"Did you actually read the note?" Jack asked.
"Yeah, I did. 'Under no circumstances go to P4C-970. Take care of my daughter. Jack O'Neill.' What does it mean?"
"From what I got from her before I was called here, she is my daughter, and I have raised her since she was four. For the past five years we have been living in exile in Minnesota because I disagreed with a popular alien ally," Jack started.
"Who's her mother, Jack?" Hammond asked. Jack muttered something. "What was that? Didn't catch it."
"It's Carter, sir. Her mother is Major Carter."
"That presents a problem," Hammond said.
"You think?" Jack asked, sarcastically.