Dimension!

(Could well be a sequel. To a sequel. So it's the third one, then. For reference.)

Two men, one shorter, one taller, stopped short on the edge of a vast crater. Behind them was only desolation, miles and miles of once-bricks turned into powder and then to glass by the force of the Big Boom; an uneven, treacherous surface, broken intermittently by sheets of shattered, pitch-black metal, marking the remains of Combine structures. Only at the edge of vision could any sign of the city that once was be seen.

Turning their gaze to the crater, the two men saw destruction on another scale.

A tower had once stood there; a tower built by the Combine, who held dominion over Earth after the decisive Seven Hour War. From it they had ruled over the surrounding city. Its flesh was made of their blue-black metal, and from deep beneath the earth it rose to the very heavens. But in the midst of revolution, a saboteur had gained entry to the tower - the Citadel, as it was known - and wreaked incalculable harm upon its workings. Less than two days later, the Big Boom occurred, high atop the Citadel; the city was laid waste, blasted into rubble and glass. And the Citadel itself - a structure weighing hundreds of thousands of tons - fell.

The two men stood for a moment longer on the edge of the crater, looking down at the broken Citadel. Strange swirls seemed to move at the edge of perception, like translucent blue scarves.

"So, remind me," the taller man said to the shorter. "What were we sent here to look for?"

The shorter man gave the taller a look. "You remember the briefing they gave us, right before they shoved us out the door?"

"No."

"Really?"

"Might've been drunk at the time."

"****."

The taller man offered no response.

The shorter man rubbed his forehead; then he sighed. "Look, let's just get down there. It's not something that needs a lot of explaining."

The taller man nodded and agreed. They began to walk down the side of the crater, on the lookout for worse-fused ground that might give way under their weight.

"You didn't bring any of the stuff, did you?" the shorter man asked.

"No, no," the taller man denied emphatically. "Drank my last drop before we left. Had been saving it for a special occasion, and what with recent events and all... seemed like a good time."

They walked on a few more meters, watching their footing.

"Shame," the shorter man grumbled. "Could use some liquor right now."

"Can't you tell me what we're looking for?" the taller man asked again.

The shorter man shook his head. "Nah, then you'd be just as bad as me. Need someone who's cool and collected, not terrified out of their wits."

The taller man took his eyes of the ground, taking the time to look his companion up and down. "You look fine," he said.

The shorter man grunted.

-

As they got closer to the center of the crater, strange sights - transient, barely visible even for the short span they lasted - began to appear in the air. Green skies streaked with nebulae, queer shapes moving on islands floating in midair, manta rays soaring high above...

The taller man, after seeing several, tapped his companion on the shoulder. "Pardon me," he said, "But am I seeing things, or are we in some kind of interdimensional hotspot that we should flee as fast as our legs can carry us?"

The shorter man looked up with a noise of surprise. "Oh, strange apparations are starting to appear?" he asked.

His companion nodded emphatically.

"Good," the shorter man said. "That means we're getting close."

"What the hell are we looking for?" the taller man asked for the third time.

"Xen." the shorter man replied.

After a pause, in which no further response seemed forthcoming, the taller man said: "Xen."

"Yes," the shorter man said. "Xen. Interdimensional borderworld, binding medium of the Portal Storms, potential home of powerful allies? All that stuff that they said at the meeting?"

"Look, man!" the taller man said defensively. "It's the end of the world! The Free Man has come, the Citadel has fallen, the Combine are on the run. Can't a man drink at a time like that?"

"NOT WHEN HE HAS A MISSION IN HALF AN HOUR!" the shorter man yelled.

The taller man cringed. "All right," he said. "So we're looking for some sort of interdimensional leak to Xen. Caused by the Big Boom, I guess. What do we do when we get there?"

"We go in," the shorter man said.

"Into another dimension?" the taller man asked, incredulous.

"Yes."

"How do we know that we won't just die instantly? From, you know, stepping into a heatless, airless vacuum? The glimpses we've been getting don't look very hospitable."

"There were expeditions sent in, years ago."

"I think I remember this bit. Weren't they wearing sealed, pressurized hazardous environment suits?"

"That was just for caution. We'll be fine."

After a pause: "Wait. Isn't Xen the place that headcrabs come from? Also barnacles, ant-lions, bullsquids, and half a dozen other species of hideous man-eating alien monsters?"

"You make it sound like they'll all be lining up to eat us as soon as we step through."

"For all we know, they will!"

"Aren't you supposed to be the cool, collected one here?"

"Now you're just being mean!"

"Too bad. We're here."

The taller man and the shorter man examined the portal to Xen.

"This... looks like a floating, green plasma-star-thing," the taller man finally observed. "With weird drifty arms that swirl around it. This does not look like a portal."

"How would you know?" the shorter man asked.

"Wouldn't you be able to see stuff through it if it was a portal?" the taller man asked. "Unless, you know, it was the portal to the inside of a star. In which case I definitely don't want to step through."

They stood a while longer, looking at it.

"Well, it seems kinda like what they told us to expect," the shorter man observed.

"What was that?"

"'Big. Green. Can't miss it.'"

There was another moment of silence.

"Leap of faith!" the shorter man cried, and stepped forward.

He flared green and vanished.

The taller man looked down. "Not even ashes," he noted.

He turned around, looking at the edge of the crater. "Not as far as it seemed," he noted. "I could just say that the portal vanished after him or something. Weird anomaly, very sad, and I'm home free. Fighting the Combine, with all their hyper-advanced technology and resources, and us with whatever we can scavenge. Just like the old days."

He looked at the green shape again.

"**** it!" he cried defiantly, and stepped forward. He, too, flared green, and vanished.

The portal waited a moment, and then shrank into nothingness.

If this alarmed the men on the other side, nothing of them remained on Earth to show it.