"There was nothing on the planet." McKay began. "I'm not even sure why the ancients built a gate on that planet. There wasn't even a sign that there ever was life there."
Weir was puzzled. "Do you think maybe the ancients built a gate there when the Wraith were attacking them. Maybe that planet was a good hideout for the ancients because the Wraith wouldn't think there was any life on such a desolate planet. But I guess that doesn't really matter. Well, that's all."
As everyone was getting up to leave, Sheppard thought he saw someone walking around Atlantis that looked like McKay, even though McKay was right next to him. He rushed out and over to the place where he saw the double. There was no one there. But what he did see was puzzling. When the SGC teams arrived at Atlantis, all of the plants there had died. But there was a living plant. "I guess someone brought a plant through the gate." he muttered to himself and left. The plant was idle until Sheppard was completely out of view. It melted down into a silvery liquid, and solidified to look exactly like Major Sheppard. It walked around and looked at all of the other people nearby. When hidden out of view again, it could transform into all of the figures it had seen. It finally chose to be in the form of Sheppard and wandered Atlantis.
The real Major Sheppard was in his quarters preparing for trade negotiations with the Herkhem, a small and somewhat strangecivilization encountered on one of the planets with a Stargate. They were going to give the Herkhem some of the building materials found on Atlantis in exchange for food. The Herkhem were a temperamental people who were easily offended. Sheppard was practicing their greeting ritual which Teyla taught to him, because they would be insulted if anyone spoke before the ritual was completed. Part of that ritual involved giving a small trinket as a gift. According to Teyla, they were very fond of shiny objects, so Sheppard and Weir decided that a bullet would be an acceptable gift. It was small, shiny, and the Herkhem did not know that it was used to kill people. "What bizarre people." Sheppard thought. Sheppard was going to ask Weir when they were going to be leaving when the imposter snuck in with out being noticed. It assumed the form of McKay and grabbed Sheppard by the shoulder. Sheppard spun around and saw McKay behind him.
"Holy shit!" he exclaimed. "Don't do that again." The phony McKay smirked."I mean it McKay!" Sheppard said as he left.
After dark, the imposter, in the form of Sheppard, was accessing the main computer because someone forgot to activate the security lock. The imposter read the files of every person and every mission. The creature had an uncanny ability to retain information. After reading the last file, the imposter crept to a corner and transformed into a mosquito sized, black beetle found on the planet of its origin, the planet where it hitched a ride with McKay into Atlantis.
The next morning, a gate travel was sceduled to negotiate trade with the Herkhem. The alien, still the beetle, was trying to find a way to hitch a ride through the gate. It crawled over by the gate where a large throng of people was busy at work. Supplies were being packed, groups were assembling, and Dr. McKay was franticallytrying to find a way to ask the Herkhem if he could explore the planet without insulting them. Lieutenant Ford was standing in front of the gate, ready to go through. The alien crawled onto Ford's boot and did not move. After a few minutes, everyone was ready to depart. The gate was activated, and the alien was carried through onto the Herkhem's planet.