This had to be the right one.

God, please, let it be the right one.

The Goa’uld couldn’t be held off much longer. He knew that, even without returning to look. The SGC had already suffered massive casualties by the time he left. They would surely be on their last leg by now - if any of them were still alive at all.

Knowing that the future of everything he held dear depended on this one last mission, he reached out and touched the mirror.

“Sir?”

Colonel Jack O’Neill looked up, his face showing slight annoyance at being interrupted right in the middle of a bite of Froot Loops. The young woman who had spoken looked nervous, her posture cardboard stiff.

“Yes?” He shoved the last mouthful of sugary cereal into his mouth and stood up.

“A young man was discovered in a top secret government facility last night,” the woman recited, seeming to have memorized what she was to say. “He says he came through the Quantum Mirror and is demanding to see you.”

Jack sighed deeply. Sometimes he’d like to go and blow up that damn mirror himself - it definitely caused more trouble than it was worth.

“Where’s he at?” The CO of SG-1 asked, ignoring the curiosity evident on the faces of two of his team members, who were standing next to him. The third team member may have been curious also, or angry, or sad, or singing the chorus of “Twist and Shout” over and over in his head. From his expression, it was impossible to tell.

The nervous airman stood straighter, if that was possible. “They brought him here, sir,” she said. “He’s being brought down now. He says it’s very urgent.”

Oh, please, not another ‘they’re coming to destroy us’ message, O’Neill thought, then felt a little bit contrite. As it had turned out, Daniel had been right, and his little alternate reality escapade had, in effect, saved the world.

The young man, dark-haired and a little shorter than O’Neill himself, was led into the room, closely followed by two SFs just in case he suddenly went ballistic and tried to blow them all to kingdom come.

O’Neill froze.

Sam Carter looked at the young intruder, then back to her commanding officer in puzzlement. There was something familiar about the young man, something about his face, but she couldn’t quite place it.

Oh my God, he looked like - surely he couldn’t be -

“Charlie,” O’Neill whispered.

“Dad!” Charlie O’Neill blurted without thinking, then immediately blushed in embarrassment. “I mean Colonel O’Neill,” he stammered. “Sorry about that.” He was somewhat surprised by the shell-shocked expression on this Jack O’Neill’s face.

Finally, the Colonel seemed to gather his thoughts. Clearing his throat, he said carefully, “Charlie. What brings you to our reality?”

Saying a quick prayer under his breath, the dark-haired teenager rushed into his rehearsed explanation. “In my reality, the Goa’uld have attacked Earth and when I left, the SGC was on the brink of defeat. On a number of planets, we’ve heard of a benevolent alien race which protects humans against the Goa’uld, but we’ve never been able to find a way to contact them.”

“The Asgard?” Daniel Jackson questioned.

Charlie looked toward the unfamiliar face and nodded. “Do you have a way to contact them?” He asked hopefully. “This is the fourth reality I’ve visited and none of the others could help. One of them was in worse shape than mine, if that’s possible.”

“We can help you contact the Asgard,” Major Carter put in. Charlie nearly collapsed from relief. “Actually, you’re not the first alternate reality we’ve helped,” the blond Major added.

“Oh, thank God.” Charlie closed his brown eyes briefly, oblivious to the agonized expression on the face of the man standing across from him. “Thank you, God.”

After the mission had been approved by General Hammond, SG-1 and its alternate-reality visitor headed for the locker rooms to gear up. Charlie couldn’t help but think that this version of his father was awfully quiet.

“I’m glad your General Hammond approved this mission so quickly,” he said as Jack dug through his locker to find a fresh shirt for the younger man. “Your reality probably already knows this, but I’d die of entropic cascade failure if I stayed here too long.”

Jack’s face looked pinched and he didn’t comment, just tossed Charlie a shirt. When the teenager pulled his own grimy brown t-shirt over his head, O’Neill caught sight of an ugly scar on the young man’s side and stopped mid motion.

“Where’d you get that?” He asked softly.

Charlie glanced down. “Oh, that. When I was ten years old, I accidentally shot myself with your - with my dad’s pistol.” Misunderstanding Jack’s expression, he hurried on, “Believe me, my dad was just as horrified about it as you are. I don’t think he’s ever forgiven himself.” Tilting his head slightly to the side, he asked, “That didn’t happen here?”

Again the haunted look, the pain surfacing in those oh-so-familiar brown eyes. “Oh, it happened here,” Jack said hollowly. “And don’t worry about entropic cascade failure. It won’t be a problem.”

Charlie stared.

No wonder the man had been so quiet.

No wonder he’d looked so shocked upon seeing Charlie’s face.

For him, Charlie O’Neill had been dead for eight years.

His mind spinning, Charlie tried to figure out what had made the difference, what small trick of fate had allowed him to live while this Charlie died. “The gun went off as soon as I picked it up,” he used, hardly aware he was speaking aloud. “Dad always said it had a hair trigger.”

A small tortured sound escaped Jack’s throat and he pressed his face hard against the cold metal of his locker door.

Dad always said it had a hair trigger ...

A hair trigger ...

He’d had it fixed, that trigger, less than a month before Charlie - his Charlie - died.

A hair trigger. It would have saved his son ...

Aware of the devastating effect his words had had, but not quite sure why, Charlie cleared his throat uncomfortably. “Dad had thought about getting that trigger fixed,” he said timidly. “He still feels guilty about it, says maybe if he’d gotten it fixed, I wouldn’t have - ”

“No!” Jack’s voice was fierce, making Charlie jump. The Colonel’s eyes were dark and empty, and softening his voice a little, he added, “No. He should be thankful he didn’t get it fixed. He should be ... ”

His voice trailed off, and he turned and walked out of the locker room, leaving Charlie staring after him.

Lieutenant Colonel Jack O’Neill turned sharply into a doorway on his left, a staff blast narrowly missing him. He slammed the door and locked it behind him, knowing it would barely slow down the Jaffa in hot pursuit.

The remaining members of the SGC knew they couldn’t hold out much longer. Lieutenant Colonel Samantha Carter, the CO of SG-5, was the only remaining member of her team, just as he was the only remaining member of his, SG-1. All the other teams had at least two members remaining, but almost every one had lost someone.

“Carter, Ferretti, let’s go,” O’Neill shouted, bursting into the room. “We can’t hold them back. They’re right on my tail.”

“Jack,” Catherine Langford said, “we’d have a better chance if we - ”

“No,” O’Neill replied bluntly. “I’m sorry, Catherine, but we stay on the same level as the Quantum Mirror. It’s our only chance now.”

As he took his wife Sara by the hand and led her and the others out of the room, Lt. Colonel O’Neill silently begged, Come on, Charlie! We need you NOW!

“This is familiar,” Colonel Jack O’Neill mumbled under his breath upon stepping ‘through the looking glass’ into another reality.

This SGC was ravaged, its walls blasted and crumbling. If these people were still alive, which was doubtful, they were in a hell of a lot of trouble. Charlie’s eyes were wide; he looked scared, and Jack didn’t blame him. He, too, was afraid they were too late.

Following Charlie’s devastating revelation, O’Neill had slipped into full soldier mode - cool, emotionless, completely focused on the task at hand. If they were to survive this, he couldn’t lose concentration for even a second.

The halls were crawling with Jaffa, and several times SG-1 nearly collided head-on with a patrol. By the time they finally reached relative safety, every member of the small group had said a prayer to someone or something.

“Charlie! Thank God.” Lt. Colonel Jack O’Neill stepped forward and hugged his son tightly. Looking beyond the boy, he could barely conceal his surprise. “Whoa, you must be - ”

“You. Yeah. It’s weird, I know.” The two Jacks contemplated each other for a moment. The Lt. Colonel had a noticeable limp, but no scar over his eyebrow. The biggest difference, however, was also the hardest to describe - it was in their eyes. Lt. Colonel O’Neill’s eyes had viewed things no man should ever have to see, but they lacked the shadow of half-hidden agony in the eyes of his counterpart.

The life-saving communications device was handed over, the Carters contemplated each other, and Daniel wondered why he never seemed to join the Stargate program in alternate realities. Colonel O’Neill shook the hand of Lt. Colonel O’Neill and said softly, “Thank you.”

“For ... ?”

Colonel O’Neill tipped his head toward Charlie. “For letting me see what my son would have been like at eighteen. For not getting a hair trigger fixed eight years ago.”

“My God,” the Lt. Colonel whispered after a moment, “you mean if I’d - ?”

“Yes.” Jack nodded and cast one last lingering glance at the young man who could have been his son. “Thank God you didn’t. Thank Him every day of your life.” He attempted a smile, which fell flat. “Take care of Charlie for me, okay?”

He didn’t look back when they left, because he knew if he did, he’d never be able to leave.

And that night, while the rest of his team slept and an alternate reality was saved by the Asgard, Colonel Jack O’Neill stared at the ceiling and thought of hair triggers and lost little boys.