A/N: I do not own these characters or the shows they come from. I'm just borrowing them for a bit.

A/N 2: Stormatcher, of course you are right. I just kinda thought it would be cool for the Smallville crew to see the Stargate in all its glory, but I have gone back and fixed the chapter, thanks.

A/N 3: The Stargate itself is cool. Period. Clark is no more immune to that than anyone else. Because I said so. (author grins)

A/N 4: Okay, a little back story will be up first. I'm going to try and show a way that explains about how Clark could get hurt, but it might not fully make sense. Ah well, hope you enjoy anyway. Bye for now!

A little before this story started…

T'Rog tapped his main arm claws against the console. The displayed data didn't change. He grunted. His vessel was running out of fuel, and if he didn't find a planet to land on soon he would drift in space forever. He tapped a few controls, this time with purpose. He made a pleased noise. There was a solar system nearby, with a yellow sun and many planets. Using some of his precious fuel he directed his ship into the system. The first few planets were unsuitable. Then T'Rog seemed to smile. The third planet from the system's sun could sustain life. He cocked his head at the readings on his display. Apparently it already did have life. The fuel sensor made a beeping noise. He let out a low growl. It seemed that there wasn't much choice.

As his vessel came closer to the planet, it began to pick up more readings. There was a low-level radiation coming from one part. T'Rog tapped a few controls, and the data clarified a little. He was still too far away, but it looked as if this planet had been hit recently by chunks of space rock. Perhaps this area would be clear of indigenous life? He urged his ship onto that heading. Just before he entered the planet's atmosphere an alarm went off. Snarling, he looked at its display. Another ship? Perhaps he wasn't the first to visit this place. He would have to check it out. T'Rog could only hope it wasn't an enemy. He rolled his good luck charm around in his main hands, his claws digging into the green rock. He'd picked it up on his last port of call. Apparently some poor planet had blown up and pieces were all that remained of its advanced race. It was supposed to protect travelers from harm. If so, his ship should land in one piece. He secured the rock under his seat, not noticing that flecks of green adorned his claws.

The entry was swift, and his craft landed, furrowing into a field. After things settled, he got out, after securing the ship and setting the homing beacon on a timer. With no fuel, his ship was not leaving this planet on its own. Perhaps another of his people had escaped and survived like him and would find him. The chances were low, but stranger things had been known to happen. He began to explore his surroundings, hissing when he found a structure next to his ship. So, this area was not devoid of life-apparently intelligent. He went inside the structure, when he heard movement outside. He looked towards his ship, and saw one of them. One of the ones that had killed his world and enslaved his people. Snarling, T'Rog attacked.

Present time…

Clark, his parents, and Lex had finally retired to their suite. The Smallville quartet had managed to eat a light snack, along with SG-1. Sam smiled at them, and told them that there would be more explanations in the morning, and to try and get some sleep. Jonathan doubted that they would actually get much rest, but he thanked the Major and then went inside their room. The door closed, and Clark just looked at his parents. He swallowed.

"They go to other worlds." He said.

"They've met aliens. One even works with them."

Martha looked at Jonathan, a question in her eyes.

Jonathan shrugged, not knowing what to say.

Lex interrupted.

"Wait a minute," he said, looking around.

"Clark, you're here for them to keep an eye on you. I would be surprised if they weren't doing it right now."

He whispered into Clark's ear.

"Take a look around and see if you can spot anything." Lex emphasized the see.

Clark stared at his friend, then nodded and shifted his eyes to x-ray.

He scanned the room, and then repeated the scan in the other rooms.

He came back out to the front room and whispered to Lex and his parents.

"One camera is hidden in each room. None in the bathroom, though. They aren't lit up; I don't think they're on yet."

Jonathan grunted, outraged.

"How dare they do that? Clark saved their lives!"

"I would imagine it to be standard procedure, at the level of secrecy that has to be kept here." Lex said.

"Besides, unless he's kept in an isolation room, how else are they going to know if Clark develops any reactions to the creature's hurting him?"

As if to bring Lex's point home, Clark began coughing.

Alarmed, Martha rushed to her son.

"Honey, what's wrong?"

Eyes wide, Clark couldn't answer, and Lex grabbed his friend and helped him to the bathroom, where Clark leaned over the sink.

He coughed, and spat green phlegm into the basin.

Shocked, he continued to cough and expel the substance until he felt better, much better than he had been feeling, even though he hadn't realized he didn't feel well before.

He rinsed his mouth, and gratefully accepted the bottle of water Lex had raced to get for him from his luggage. He didn't want to take chances on tap water.

"Better?" Lex asked.

Clark nodded.

"It must have been the creature" he said, "I feel normal now."

Martha sighed in relief, and Jonathan gripped his son's shoulder.

"Don't scare us like that again." He said gruffly.

Clark smiled at his parents, and then looked seriously at Lex.

"Thanks," he said to his friend, "for everything."

Lex shrugged.

"I'm just trying to look out for you. You've saved my life and done the same for me. "

"I know." Clark nodded.

They sat on a sofa and chairs in the front room. None of them felt like sleeping yet.

"Mom, Dad," Clark said, looking earnestly at Martha and Jonathan. "They're going to find out from my blood anyway. I trust Col. O'Neill, and I don't think he'd let anything bad happen to me. He's friends with an alien already."

Jonathan opened his mouth to object, but Clark went on.

"Lex deserves to know first. He'll protect me. He already has."

His parents looked at each other, worried, and then Martha nodded decisively and smiled at her son and Lex.

Lex had followed the exchange, and suddenly realized what Clark was about to reveal.

He swallowed.

"Clark, are you sure?" he asked.

To be continued. (thunder rolls and lightning crackles)

A/N add-on: Spoiler alert! ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

In the fourth season episode of Smallville where Clark ingests Kryptonite lemonade he coughs it out I think, been awhile since I saw that ep. To explain things for this chapter, kryptonite entered his bloodstream from the creature's claws and made him weaker and susceptible to being harmed by said creature, the Zat gun and the Reetou. His body however was working on healing itself and expelling the noxious substance, it just took some time. Now that it's out of his system he's his normal invulnerable self. He didn't notice the effects because it was a very small amount and he kind of had his mind on other things. I haven't read the comics so I apologize for any inconsistencies. I hope that clears things up. We now return you to your regularly scheduled programming. Beep!

A/N postscript: I stand corrected. In the season 4 ep Clark gets beat up and the Kryptonite dribbles out his nose. I still think the coughing was more dramatic, though so I'm keeping it. Ta-ta!