Somebody - maybe N.I.D. - want to take out Jack - maybe revenge. They inject him with that drug from the… which made the injected person younger and delete their memories. They didn't want to kill him - maybe in a hope they will be able to use him in the future: the ancient gene or knowledge or black mail material…. But Jack didn't lost his skills - fighting, maybe technical skills - he managed to escape, and try to hid in one of the bigger city with his kidnapper after him. His half brother or cousin MacGyver get a message from the Air Force that Jack died or went M.I.A. or something. He start to investigation, he maybe snake in the SGC and meet with Jack's team or Hammond.

One of the missions went wrong and Jack was left behind. He was hit by a Jaffa's staff weapon and was pursuit died.
- A God of plays or games captured him. The god has an arena and he force his prisoners to fight for life or death. There could be free warriors as well who want to try themselves out or to prove their worth. Jack becomes the Champion but he didn't want to fight. Maybe he save some kids life and the god black mail him with the child or other children life. - The story could be slash, mpreg, het or gen. DE-age if the champion's reward is the youth. The team won't come across him for years, for example some Toak'ra mission the gate to this world. Will they recognize him, How they will react? Will they able to rescue him and his ward/family.
- Or the god of youth made up his army from his captured warriors (deaged and re-programmed) Jack is in his usually skeptic self, inspite of his lost memories. He feel there is more, with his friend(s) he snake in the castle closed part where they discover the mind-wiping and deaging machine. They manage to throw over the God and start a revolution or something.

De-aged story the whole team is de-aged - expect Teal'c he isn't there - impend of time line who is there Jack, Daniel, Sam and Jonas/Cameron/or nobody. They were captured and the God want to keep them as a pet and something. He de-aged them but they managed to escape. They live in the woods. Some times later - weeks, mounts or years your choose. Someone find them: Jacob is on Toak'ra mission or Bratac or some random SG team. How will they cope? Who will be their guardian? The story starts here or end? Can they change back?

Daniel touch something he shouldn't and Jack pay for it.
- Jack will be de-aged -it couldn't be reversed - Up to you if he have his memory or not. Who will rise Jack again? (I would like to see one where not one of his team member. And you should explain why. For example they are busy with their work and they couldn't take in a small child or just didn't want. I think it would be interesting if he would be rise by Hammond or Janet or one of the other teams leader or a canon character.)
- Maybe de-aged, and ancient gene when Daniel touch something a beam hit Jack which vitalize his ancient powers.

I always wondered what would have happened if mini-Jack is the really Jack O'Neill. What would have happened with him, would they have let him stay with SG1 or SGC at all. How others would have treated him? How would have his life  and the galaxy fate changed?

While both the Jaffa and the Toak'ra on the alpha site, jack got a message he was withdraw from his position as 2IC of SGC. The new man is his old black ops CO who now a General. They have a bad past? What will it cause to Jack? Jack will be called back to a newly formed black ops team which will haunt down the Goaulds. - maybe de-aged by the drug without the memory loss.

 Everything change, the original SG1 gone, Sam built her normal life, Daniel gone to Atlantis and Teal'c to his Jaffa business. And Jack remind alone as the SGC's CO, how will he cope with the events? Who will become the member of the next SG1. - Maybe Cassy, Haley, and de-agedJack/cloneJack. How will they do? How they will become a team ? What will happen if the original members come back?

Crossover - Harry Potter
- Severus Snape and Jack O'Neill as relatives (cousins or brothers) - Severus rescued Harry Potter from his Death Eater captivation and he bring the boy with him the only safe place he could think (Hogwarts not count, they couldn't go there for some reason, maybe there is a spy.) And his worlds collide when Harry meet Jack. It is up to you if Jack is a wizard or squib or just plain muggli. If Sev go to work with Jack? What Severus will do there? How will Jack's team react to Jack's 'forgotten' relative?
- Severus Snape and Jack O'Neill as relatives (cousins or brothers) - after HBP Sev and Draco on run. The only place Sev could go to his brother, Jack. What would be Draco reaction be to this muggli life style.
- Or after the II. Voldemort War Severus want to go to a place where nobody could judge him.
- A few select member of the wizarding world knew about the Stargate, a secret society were their thought sanctuaries to guard the gate. After Voldemort rise (first, second your choose) their numbers was very small when they get the news about the Stargate reopen Dumbledor send Severus Snape (or Sev is the society's member) to investigate how much the mugglis know and try to stop the goauld invasion on Earth. He managed to become a member of the SGC somehow.
- Or maybe Voldemort sometimes ago become a goauld, The Order need some help with this new information and summon a warrior to help their case or who have the information about what a goauld is.

Crossover - House MD -  a strange disaster is in the SGC, the doctors couldn't find what it is. Jack remember his old collage friend from the Air Force Academy, whose name is Greg House. What will say the hospital and House when some SF come for  (Captain) House?

Crossover - Indian Jones - SG1 series 8 - When Jacob/Selmac dieing Jack remember when his father talked about the Saint Grall and an other artifice which could give back youth and life. They need Indiana Diary which he won't give them expect if they will bring him with them. - In the end maybe de-aged Indian, Jack, Jacob/Selmac. Maybe Jack's father/grandfather is Indiana.

Crossover - James Bond -maybe after Tomorrow Never Die - From Jack's past an old friend come to SGC. James bond is searching for where the bad guy get the sun gun technology. The leads come to Colorado Springs.

Crossover - MacGyver - Jack is MacGyver. And SG1 run in the very alive Mordoc and Jack say: "For crying out loud. In this Galaxy nobody could stay died."

Crossover - Pretender - Not Jarod was the first who escaped, when Jack (and MacGyver) were 8 he (they) run away from the Center, his (their) road go to Minnesota where he (they) was adopted. What if his past come back to haunt him.

Crossover - NCIS - The NCIS went to investigate a Marin's murder where Jack was hurt as well (it was maybe an assassin attempt on his life) so he start to investigate as well. Jethro as Jack half-bother.