A/N: Okay, show of hands, who remembers the 90's sci-fi show Sliders? It had such a great premise, but had lots of problems. It was canceled, picked up by another network, and along the way, lost all but one of the original cast. It still deserves some love, though, and if you're interested, it looks like it just became available on Netflix. I ignored/changed some of the later canon of Sliders, but I hope you like my story anyway!

The bus trip should have been the first thing that tipped her off. It was a weird thing to be running through her mind as Penny tried to fend off the attack of the ten-foot bird (which resembled a blue ostrich with sharp teeth) with nothing more than a pointed stick, but that's what she was thinking. She managed to jab her improvised spear up into the bird's open mouth. It screamed and shook its head, spraying blood everywhere, and then retreated with a loud shriek.

"How much longer, Sheldon?" Penny cried, panting.

"Fourteen minutes, twenty-eight seconds," he called back, checking the bulky device in his hand.

"Think we can avoid those monster birds for another fifteen minutes?" she asked dubiously.

He pointed upwards into the leafy canopy that stretched above their heads. "I think we'll have to climb," he said.

Penny made a face to show what she thought of that idea. "What if there's also monster spiders and monster snakes?"

He shook his head. "We'll have to risk it."

As Penny pulled herself upward, scraping elbows and palms on the rough tree bark, she wondered for the thousandth time if this all could have been avoided somehow. If only the contents of that dusty cardboard box had turned out to be a time-traveling machine instead of that stupid alternate-reality-portal thingy. She should have known something strange was going on when Sheldon was willing to take three buses, braving exposure to all sorts of public germs, to get to an estate sale. The deceased was one Amanda Mallory, mother to the late Quinn Mallory, a once-promising physics student with unconventional ideas. Quinn had gone missing over twenty years ago, and there were many rumors about his disappearance. One of them said that Mallory had managed to invent a time-traveling device. Sheldon, an avid Doctor Who fan with far too much disposable income, had gone to the estate sale and, for a little over fifty bucks, had purchased an old box full of assorted electronic parts. He had explained all this to Penny as he was unpacking the contents of the box. She commented wryly that she was sure he had overpaid for it, whatever the price, since all the technology was bound to be obsolete—except her term was "worthless crap".

Sheldon had immediately started tinkering with some of the devices he purchased, but it was weeks before he got one of them repaired. He stared in astonishment at the whirling, funnel-shaped vortex hovering in the air in front of him. It worked! He was so excited, he couldn't wait to tell someone. Leonard had gone out to a movie with Raj and Howard, but he was sure they would want to see this right away. He picked up his cell phone and speed-dialed Leonard. It went straight to voicemail. Sheldon groaned in frustration. What a wretched time for Leonard's phone to be off, he thought irritably. He tried calling Raj with the same result. Howard was only a valued acquaintance, but Sheldon would seriously consider upgrading his status to that of friend if only his phone was on. He never got the chance to find out. He heard the door open, and Penny called out, "Hey Sheldon, how come you're late for laundry... Holy crap on a cracker, what is that thing?"

"I believe it is a time traveling portal," Sheldon said. His voice was unsteady, but he looked at that mysterious vortex worshipfully, like it was the answer to life, the universe and everything.

She dropped her laundry basket on the floor with a thud. "Uh... is that a joke? Does it actually work?"

"I haven't gotten to the experimental testing phase yet. I just generated this portal a few minutes ago," Sheldon replied, picking up the device and pressing a few buttons.

"Wow, this is frickin' awesome," Penny enthused, lifting a finger to poke at the strange phenomenon.

"Don't touch that!" cried Sheldon, but it was too late. Before his horrified eyes, her figure seemed to stretch and elongate as she was pulled inexorably into the vortex. Penny! He only had a split second to act. Clutching the remote tightly in one hand, he grabbed her wrist with his other hand. The portal yawned open like a hungry maw and devoured both of them before shrinking down into nothingness.

They had been traveling together ever since. It didn't take Sheldon long to deduce that the device allowed them to visit alternate dimensions instead of traveling through time. He had been disappointed for only a moment before getting caught up in the excitement of the possibilities of this new technology. Penny just wanted him to figure out the device so they could get back to Pasadena... their Pasadena. Apparently, the device with which Sheldon had been experimenting was a crude prototype. It had never been configured to store the information needed to return them to their own reality, so they roamed through parallel dimensions trying to find their way back home.

In the past eight months, they had visited dozens of different Earths. Every time, they landed in the same geographic location, but in a parallel universe. Each world was unique. Some worlds were not that different from theirs. Most of the other ones were downright scary. In one alternate world, California was a prison state where political prisoners were exiled. In another one, they had been chased by strange mutated creatures that looked like large insects. Once, they had landed in the middle of a swift-flowing river and almost drowned.

Penny couldn't wait to leave this world, a primeval nightmare dominated by giant birds with razor-sharp teeth and yard-long poisonous scorpions. She reached down to help Sheldon up to a wide branch, and he accepted her help without comment. They had both changed a lot in the last several months. For one thing, they had become much more dependent on each other, learning to respect each other's strengths and rely on their instincts to keep them alive. Touching was another thing that Sheldon had simply had to get used to. Penny held his hand tightly whenever they had to jump through a portal and clung to him when she was scared. He tried not to admit to himself that sometimes he drew comfort from her touch as well.

Before the accident that had stranded them far from home, Sheldon had reluctantly starting dating Amy, a female scientist. He had liked her enough to make changes to his schedule to include date nights, but he still cringed when she insisted on holding his hand. All he really wanted was for them to continue to spend time together, but she had constantly been pressuring him for a more physical relationship. He hadn't been ready for it, and wasn't sure he ever would be, at least with her.

He glanced over at Penny. She rarely mentioned Leonard either. They both knew that by now, even if they could get back home, there was a good chance he had moved on and was dating someone new. Penny had once confided that she had agreed to get back together with Leonard in a moment of weakness. She had been feeling lonely and disillusioned about her lack of progress with her acting career. Leonard's fawning attention had been the sop to her ego that she needed, even though she knew she wasn't any more in love with him than she was the first time around. She'd tried to do the right thing and let him go when it was clear he cared for her much more than she cared for him. But when her self-esteem hit an all-time low, she had agreed to a "beta test" with Leonard. Sheldon had asked her not to hurt his friend, but there was no way she could have done what he wanted. Her relationship with Leonard had been too deeply flawed and unbalanced.

Looking over at Penny, Sheldon wondered if she had been relieved as he was to find some way out of their dating dilemmas. His thoughts were interrupted by a beeping from the bulky device in his hand. He looked up to see Penny crouched on a nearby branch, guarding his back and still holding the improvised spear. He felt a sense of calm come over him, knowing that she was looking out for him. He hadn't chosen her as a traveling companion, but in retrospect, he couldn't have picked a better one.

"It's time," he murmured, pressing the buttons that would activate the portal. Penny nodded and tightened the straps on her backpack. The supplies they carried had saved their lives numerous occasions. Sheldon pointed the hand-held remote at the air beneath their feet. Penny reached over and interlaced her fingers with his as they took a deep breath and jumped into the whirling vortex.