How might the Stargate series have gone if the protagonists knew at the start all of the things they learned by the end?
While exploring Atlantis after it's return to Earth, Daniel Jackson finds a device in Janus' lab resembling the Ancient communication stones, but instead of finding himself transposed into someone else's body, he finds himself in his own body, in his personal past, skipping backward through scenes of great emotional intensity: great triumphs such as the opening of the Ark of Truth and the deployment of the Sangraal, great losses such as his first death and the death of his wife Shau're, on back and back, until he finds himself completing a lecture on his particular brand of Egyptology. Confused at first, looking around himself with surprise as he finds himself in memory after memory, he eventually relaxes and watches his memories unfold; but he pauses at that last scene, on stage at his old lecture as the last of his audience walk out, unwittingly exercising control over the Ancient device connecting him here, and reminisces on this being the moment that everything in his life changed, the moment just before he learned of the Stargate program.
He walks outside as he remembers doing, stands in the rain waiting for a cab, struck by the verisimilitude of this immersive memory recalled to life, and waits to see if Catherine Langford will arrive to invite him to join the Stargate program. She arrives just as expected, and he smiles as she offers him a remarkable opportunity... but, as he once did but for different reasons, he begins to decline her offer out of hand, having had enough of this... whatever it is... and attempts to disengage from the Ancient device by force of thought. Nothing happens, and bewildered, he speaks to the air, "End. Disengage. Uh... Disconnect!" He gestures at the sky in exasperation, expecting some kind of response. Catherine looks at him with concern and asks if he is alright. Concerned himself, he claims to be fine, and gets in the car with her anyway.
As they drive off, he touches the seats of the car, and Catherine's hand, and asks himself "Is this real?" She begins to explain to him that this is a very real opportunity indeed, and many more wondrous things will soon follow... but he interrupts her and apologises and explains that he meant, is this actually real? Is she really Catherine Langford, is it really 1995, or is this just some memory brough to life by one of Janus' devices? She doesn't understand what he is asking, and he brushes it off for now and says that he is confused, and she should never mind, "just take me to the SGC". "The what?" she asks. "Take me... wherever you're taking me" he resignedly clarifies.
Later, at the nanscent SGC, he is shown the heiroglyphic translations they have been working on and briefed on what they need his help with. Still behaving as though he's not sure this isn't a dream, he almost absent-mindedly rattles of "Yeah yeah, it's not 'Doorway to Heaven', it's 'Stargate'; the symbols you don't recognize aren't heiroglyphs, they're constellations; together they form an address to another planet to which the device you have stored in that room" he gestures to what would become the gate room "can form a stable wormhole connecting to another device on the other end, enabling near-instantaneous transit across the galaxy.... and yes," he adds, suddenly thoughtful, "I know what the seventh symbol in the address you're trying to dial is, but don't go there. Not yet at least."
Everyone looks at him stunned, and one of the scientists asks "How can you know all this?" He doesn't reply, but instead walks to Catherine and tells her, "I... almost don't believe this myself, but if what I think has happened has happened, I can help you with this project more than you ever dreamed possible, but first I need someone to believe me, more than you already have, and I think you're the only person I can convince. Catherine," he looks at her solemnly, "Ernest is alive." She looked at him aghast, and asks how he can possibly know of Ernest. He says that he will explain how once he has proven himself correct, but for now, they need to request specific files which are currently classified, the names and locations of which he tells her, and she will find proof that her erstwhile lover Ernest Littlefield has already travelled through the Stargate in 1945. He promises her that he is alive and well, or as well as can be expected, living on another planet, and that he can help them bring him home.
The files are retrieved, and Daniel's claims are vindicated. General West demands to know how Daniel knew the contents of top secret classified files even the General himself had to demand special privilages to access. Then Daniel drops the bombshell: "I'm from the future. I don't understand the mechanism exactly, but a device built by one of the same people who built the Stargate sent me here. I wasn't expecting it, and I don't know how to get back. But now that I'm here... there's so much that can be done with the knowledge I've gained. In my timeline I've been a part of a team here called Stargate Command for the past fifteen years. I've been on hundreds of missions through the Stargate, learned... the mysteries of the universe... fought horrible battles and suffered terrible losses and though we won, with my foreknowledge you don't have to suffer those same losses. I can walk you through it all, easily. While we've been waiting for the files to come in I've been thinking, and I've got a solid plan. But first.... Catherine. Lets bring him home."
At Catherine's pleading West is willing to at least give the mission to Heliopolis a try. Daniel insists that Samantha Carter be brought in, as there will be technical difficulties dialing back which prevented Ernest's return, and she is the only one he is sure will be able to handle it. He also warns them that they will need a powerful power source to repair the dial-home device. Both advices are heeded, and both Carter and a powerful portable generator are brought along on the trip.
At Heliopolis, they recover Ernest successfully, and Daniel has proven himself to be truthful. While Sam sets about repairing the DHD with their portable power source, he uses the meeting place of the Four Great Races as background to give everyone present a brief history of the galaxy: the Stargates were built by a race called the Ancients who seeded Human life in this galaxy, and they had allies in three races called the Asgard, Nox, and Furlings, who once all met at this place. The universe is not sunshine and rainbows however, as the evil Goa'uld have enslaved most of the galaxy after abducting humans en masse from ancient Earth, and none of the aforementioned good guys can do anything about it: the Furlings are MIA, the Nox are too pacifist to do anything but hide, the Asgard are busy fighting an even worse enemy of their own in their own galaxy, and the Ancients left to yet another galaxy and got wiped out by yet another race of evil aliens after fleeing a plague sent by the worse bunch of baddies out there.
In light of all the danger out there, he explains why Earth needs to pick this fight and shouldn't just box up the Stargate now -- besides doing it for the sake of everyone else in the galaxy, and besides that the Tau'ri have the opportunity to become the greatest power in four galaxies: even though the Goa'uld are ignoring them now, in a few years the Goa'uld Anubis is going to arise and attempt to wipe out all life in the galaxy and start anew, and Earth will be lost in the process if we do nothing to stop him. Stargate Command is convinced, and ask him what his plan is.
Daniel tells them to install an Iris over the gate before they begin, for security. Then, he has them bring an even more powerful generator and the biggest portable nuclear reactor that can safely be brought through the gate back to Heliopolis. He explains that they are going to dial back to Earth, and send the reactor back, but not to the SGC: they will induce a powerful jolt of energy into the gate right as the reactor passes the event horizon, which will jump the wormhole to another Stargate on Earth, one buried in the ice in Antarctica. That is what the nuclear reactor is for: to boil away a sea of ice and quickly clear the area around the Antarctic Stargate, as they do not have time to drill-excavate the area and still get to Abydos in time to meet Ra. "Ra?" someone asks him incredulously, and he explains, "The Supreme System Lord of the Goa'uld. They visited ancient Earth and impersonated our gods, taking humans as slaves all over the galaxy. That's what was awaiting us at the address you wanted to dial first. We need to go there still, on time, but we need to be more prepared first."
The reactor is sent through, with a MALP to confirm its arrival not at the SGC, and remotely activated, beginning to melt away the ice cave surrounding the Antarctic Stargate. Daniel explains that at the Antarctic site they will find not only another Stargate, but a DHD like this one on Heliopolis, which will allow them to dial anywhere in the galaxy without having to program their computer to compensate for stellar drift, which is why they can only dial two planets from Earth at the moment. But more than that, they will find a weapons platform built by the Ancients themselves, which outmatches any armament in the Goa'uld arsenal; and even more importantly, one of the Ancients themselves, left behind to freeze in the ice when they last departed Earth.
He warns them that the team which visits the Antarctic must wear biohazard suits, as this Ancient is carrying the plague which wiped out almost all their people. But not to worry: he knows someone who can cure it. Daniel joins the team who secure the defrosted Antarctic site, and is at the side of the Ancient Ayianna when she awakens from her stasis. He explains to her, in Ancient, that he knows who she is and what has happened to her people, that he will bring her to Atlantis again and more than that they will defeat the ones who wrought the plague that ravaged her people, but first, they will need her help. He explains about the Goa'uld ravaging this galaxy, and asks her if she will help them be rid of that threat. She agrees in principle, but apologises that she is dying. Daniel says he understands, and says he can take her to someone who can help.
Ayianna is put into a biohazard suit herself, and an expedition is mounted to the Nox world. Daniel explains that though the military are free to accompany them, they cannot bring weapons or else the Nox will send them home and they will lose not only a valuable ally in the Nox but their greatest asset in Ayianna. They agree, and the expedition to the Nox world is a go. There, Daniel and Ayianna call out to the Nox in Ancient and the Nox language, until the Nox reveal themselves. Ayianna greets them as an old ally, and the Nox are pleased to see an Ancient again. Daniel introduces the Tau'ri and explains that they are allies of Ayianna and the Ancients and seek to learn from those older and wiser than themselves, but that for now Ayianna is in grave need and he understands that the Nox have power to heal her. They acknowledge this and gladly perform their healing ceremony. The hazmat suits come off, and the team departs back to the Antarctic base (as that gate with the DHD is now the primary Earth gate).
After a brief debriefing, Daniel immediately has the team turn around and head back through the gate -- they're on a tight schedule -- for their next stop. Daniel is going to bring Ayianna up to speed on where her people were before they left this plane of existence, in a way that no Human could cope with, but which her advanced physiology should be able to handle: the Ancient Repository of Knowledge on P3R-272. Daniel is correct, and Ayianna's brain is able to handle the data-dump unlike any Human brain. She is fascinated by the new knowledge, and rattles on about it in detail that nobody else understands, but the SGC are all thrilled to have the pinnacle of Ancient knowledge suddenly available to them, most of all Daniel who understands exactly what that means.
But for now they have an appointment to meet with fate on Abydos. While Ayianna stays behind manning the Ancient weapons platform, Jack, Daniel, Kawalski, and the whole old team, with Sam along for the ride this time, finally visit Abydos as in the original first mission. While Jack and Daniel visit the natives to meet Skaara, Kasuf, and Shau're as anticipated, Kawalski and the backup team remain at the pyramid and keep a watchful eye on the sky. At the first sign of Ra's ship entering orbit, they dial the gate back to Earth and radio through that the target is in range. The Antarctic team cut the connection, dial back, and Ayianna fires a burst of drone weapons through the gate, navigates them out of the pyramid, into the sky, and obliterates Ra's ship before it can even land. The backup team radio ahead to the team in the village, and Daniel informs Kasuf that Ra is dead, that his people are now free. He gladly takes Shau're for his wife again, but says that he must go now and make sure that the rest of the galaxy is safe for her.
With this proof of concept successfully accomplished, Apophis is targeted next. The team visit Chulak and covertly await Apophis's arrival, then radio through to Earth to fire. Apophis is assassinated by a single drone in front of his entire court, and Daniel informs Teal'c that he is now in command of the Free Jaffa there; and that Cronus, murderer of his father, will be their next target. Teal'c asks how this is possible, and who they are; he informs them that they are the Tau'ri, the original peoples; that the Supreme System Lord Ra is now dead by their hands, and the rest are soon to follow; and soon all Jaffa and Humans alike will be freed from their false gods. Teal'c swears his allegience to the Tau'ri, and offers whatever assistance the Free Jaffa of Chulak can provide.
To locate the remaining System Lords, Daniel plans to use the Tok'ra. To win their allegiance, the team takes zat guns from Chulak to subdue the Goa'uld queen Hathor in her tomb in Mexico, also recovering her sarcophagus intact (though Daniel strongly warns them against using it except in dire emergencies for its adverse effects). Hathor is brough, sedated, to the world where SG1 first encountered the Tok'ra, and offered as a gift to them, in addition to one more thing: the location of their lost queen Egeria on Pangar, and the promise that if Hathor can be extracted from her host, they can retrieve Egeria from her captivity in exchange for Hathor. The Tok'ra eagerly accept this offer, and travel with the Tau'ri to Pangar, where the Pangarans are more than happy to trade their old and rotting queen for a nice fresh one. In exchange for Egeria's subsequent revelation of how the Pangarans can ween themselves off the drug Tretonin they have been making from her prim'ta, they teach the Tau'ri how to make the drug, and the Tau'ri subsequently offer it to the Free Jaffa as a way to further liberate themselves from their dependence on the Goa'uld.
In exchange for all these gifts, the Tau'ri request the Tok'ra's help providing intel for targeting the System Lords, and coordinating Jaffa uprisings together with Teal'c and the Free Jaffa. The Tok'ra are expectedly hesitant to take decisive action that might disrupt the delicate status quo, despite the Tau'ri's magnificent gifts; but after investigating the recent deaths of Ra and Apophis, they decide that the Tau'ri's plan can work, and offer the assistance requested of them. As promised to Teal'c, Cronus is targeted next, spurring the Free Jaffa movement into full swing; followed by Heru'ur, the last of Ra's clan; and so on one by one the System Lords are destroyed from the safety of Earth, and the Tok'ra, Jaffa, and Humans left in their wake establish peaceful, free societies together.
The last Goa'uld to remain is of course Anubis, whose half-ascended form cannot be destroyed by mere technology. But here Ayianna's evolved power and near-ascended Ancient knowledge match Anubis's half-ascended status, and once he is found she is able to destroy him in an impressive battle of psychic powers.
With her promise to help them liberate the galaxy fulfilled, Ayianna asks Daniel to fulfill his promise: she wishes to meet her people at Atlantis and take vengeance on those who plagued their empire in the Milky Way. Daniel is happy to oblige, however there is a complication involving Atlantis. He explains the appearance of the Wraith in Pegasus, and how the Ancients of Atlantis were forced to retreat back to Earth in the end, before eventually ascending. However, Atlantis itself can still be recovered, and the Wraith can be defeated, but to get the weapons needed to do so they will first need to help out some old friends of her people: the Asgard.
Ayianna builds a generator capable of powering an intergalactic connection and dials to the Asgard homeworld. Daniel and team accompany her to make introductions on behalf of the Tau'ri again. At Daniel's prompting, the Asgard explain their predicament with the Replicators, and Ayianna offers her knowledge (from the Repository) on how to build Replicator Disruptors. The Asgard deploy the technology across their fleet and soon win their long war with the Replicators.
Daniel then explains what they want in exchange. He tells them of the Asurans in the Pegasus galaxy, and asks them to take a fleet armed with Replicator Disruptors there to destroy them, but leave their civilization intact. The Tau'ri and Ayianna accompany them, and after the devastating sneak attack against the Asurans, they gather all the ZPMs they could ever want from the remains, then dial Atlantis and bring it back online again: a gift to Ayianna, though absent the people she wished she would find there. But more than that, they also acquire an entire fleet of Asuran City Ships, and Humans with the ATA gene are identified to man and operate them all. With so many fully operation City Ships at their disposal, the Wraith are easily annihilated from orbit while they still sleep, and the Pegasus galaxy is freed. More than that, the Tau'ri are now armed to the teeth with the pinnacle of Ancient technology, and assume their role in the Alliance of Great Races.
Finally, back in the Milky Way, to fulfill the final promise to Ayianna, they dial Merlin's secret tomb. Ayianna heals Merlin, the last living Ancient from Atlantis, and is joyed to have at least one of her people left. Well again, Merlin finishes building his Sangraal. From a ZPM-powered gate, the Tau'ri finally dial to the Ori galaxy and immediately deploy the Sangraal. The team, defended from any Priors by their two near-ascended Ancients, then move to recover the Ark of Truth, which they happily show to the next Prior who comes along, oblitterating Origin in one fell swoop.
The Alliance of Four Great Races is reestablished. With the help of Ancient technology and healing powers, the Asgard are even cured of their congenital defects and are returned to a more Human-like shape, able to breed naturally again. The Nox come out of hiding, and even the lost Furlings are contacted once again. Merlin and Ayianna, together with the other three races, oversee the Tau'ri use of the fleet of Ancient City Ships, gently guiding Humanity into the fullness of their destiny. Ayianna and Merlin eventually have Ancient children of their own, who interbreed with Humans as they themselves mature, gradually restoring the Ancient civilization in every aspect by way of Humanity.