A/N Though involving a possible reunion, this story will not go the route of Journey's End. The set-up for this deviation from canon was explained in the previous story Minutes and Hours. In short, Rose will not have to face the dilemma of two Doctors. She's going to have her hands full attempting to contend with just one. ;) It also means the Dimension Cannon is going to have a more difficult time finding success with the walls of reality still intact. So a little outside help might be in order…

This will be the final multi-chapter installment to the series that began with Kings and Lords, so it feels somewhat bittersweet. But I'm excited to finally bring these two full-circle. I hope you enjoy their journey!

As always, if you're there reading along, I love hearing from you! You're the ones who make the time and effort seem worthwhile and motivate me to update consistently.

Chapter 1

With a mighty blast of power, a trans-dimensional cannon fired. A solid beam of massive energy shot from the Earth, through the stratosphere, and connected with the almighty walls which stood as a formidable blockade between universes in an attempt to breach the otherwise impenetrable.

The attempt was unsuccessful. The dimensional walls were ruthless and unyielding.

Hope for success was not yet surrendered, but achieving the impossible was about to take an alternate route, coming in a form no one anticipated.

-:-:-:-

Rose Tyler stood in the center of a stark-white room which was currently an epicenter of activity. There had been a time when simply being in this place would have made bile rise in her throat from the tormenting reminder of the moment she had first arrived here. At the far, desolate end of the room, she had beat her fists on the unyielding wall and screamed for someone, anyone, to take her back. Back to where she belonged. Back to her own world and the man she loved beyond measure. In a single agonizing instant, this room had become a prison. Now, however, this place stood as a reminder not of what she had lost, but what she was determined to once again find.

If she was successful.

So far, success had been bitterly elusive. The Dimension Cannon Project had been the result of nearly three tireless years of work. Rose Tyler had arrived in this universe with next to nothing. But she did possess one mission: find a way out. The only way out was through the impenetrable walls of reality. The walls that stood to separate her from her original universe, and most importantly, the walls that separated her from the Doctor – the man she loved, the man she had married unexpected to them both, the man with whom she had shared a sacred bond. A bond of mind and soul.

Rose had begun working for Torchwood almost immediately upon arrival, having a direct inroad to the organization through Director Pete Tyler, the parallel version of her father. 'Think I know a thing or two about aliens,' she had told the Doctor that gray, bitter day on a Norwegian beach. It was the natural choice, which had nothing to do with nepotism and everything to do with her unique qualifications. Torchwood dealt in the realm of the extraterrestrial. Rose had rare experience in this regard. Alien encounters had been her life since adulthood. Her few, all-too short years with the Doctor had given her more experience than most cultivated in a lifetime. Certainly in this arena.

And what else would she have done? Settled into the dry, fictitious role of Vitex heiress? Not bloody likely. This was a role she had to play on occasion – the little-known daughter of Peter and Jacqueline Tyler who had lived a private, guarded childhood, or so the story went – but playing such a role was not to be the sum total of her new life.

And so, Rose had joined forces with this universe's version of Torchwood. Unlike the organization in her home world, this Torchwood had been seized by the People's Republic, ending the corruption. The re-organized infrastructure was now a smaller operation than it had once been, but it was impressive just the same, with available potentials Rose never could have created on her own.

Rose had thrown herself not only into the work of defending the Earth, but finding a way back to her own. Thus, the Dimension Cannon Project was initiated. Pete Tyler had given the okay for this. He was one of the few who knew the full details of her circumstances, and he would have been hard pressed to deny her this needed resource. She and the Doctor had saved two universes at the cost of each other. He owed her this much. He owed the Doctor this much. Jackie had not been entirely keen on the idea, but she knew the Doctor and Rose deserved this, too.

His reasons for approving the project went beyond personal grounds, though. The fact was, Torchwood needed an ally when it came to dealing with alien threats. This planet was beginning to get noticed. The Cybermen and Daleks were just the beginning. There had been numerous other encounters of the alien nature since then. Some innocuous, some not. Pete had clear knowledge of just what the Doctor was capable of in this regard. If ever this Earth was in need of defending and Torchwood had exhausted its capabilities, the day would come when they would need outside help. If that help could come from someone such as the Doctor, no value could be assigned to such an asset. So if a portal could be created in which the Doctor could be reached, it was within Torchwood's best interest to do so.

With Torchwood's top scientists and engineers working on the matter, the Dimension Cannon reached the preliminary planning stages in a few short months. Bringing it into working reality had taken a few years longer. And now, finding success with the first working prototype was looking as if it would take longer still. Or possibly might never occur at all. The attempts were not having the success that had been anticipated.

At first, the greatest foreseen difficulty was thought to be in locating and crossing through to the correct parallel universe out of the mass of potential realities. They would need something that had originated from the target universe to act as a matching puzzle piece to identify the correct one – something that had developed in that world and shared its inhabitant's signature molecular structure. The answer was aptly simple: Rose. Her unique biosignature – which differed minutely on the sub-atomic level from those in this world yet shared elements with those in the parallel – would serve as a part of the Cannon's homing mechanism.

With that solved, it seemed they were just a step away from achievement. The calculations were correct, the theory behind the groundbreaking technology sound. The problem existed in the impenetrable nature of the walls of reality.

The Doctor had told Rose that crossing through from one world into the next was impossible. And even if it could be achieved, two universes could fracture and collapse in the process. Rose would do nearly anything to return to him, but she was not selfish or reckless enough to risk the destruction of worlds in order to do so. However, a theory had been devised in which a small portal could be created and stabilized with surprisingly little harm. Torchwood's scientific minds had studied the issue in length and explained things like linear particle flow and the natural stabilizing factor of combined atomic orbitals. But in short, a small but stable portal may be possible if the walls could be penetrated just so, with near-surgical precision.

The trouble was making this theory into a reality.

Three attempts had been made with the Cannon in the past week since finally bringing it online. After months and months of planning and hypothesizing, they were finally seeing the reality of what they were up against. For all of the theorized potential, success was looking more and more like a far-off fantasy.

Aside from all this, the Cannon was not the only issue Torchwood was currently facing, driving home the notion of how valuable someone like the Doctor could be at a time like this.

Four days earlier, satellites had detected something penetrating Earth's atmosphere. A short time later, unknown energy readings had been detected northeast of London, in the vicinity of Norfolk. Yet there were no physical signs of anything in the area. Something in that general vicinity was giving off unidentified energy readings, but the more focused and precise the scans, the more distorted the readings became, making it unable to be pinpointed. Teams had combed the general area but found nothing. Something was there, however. And whether it would prove harmless or detrimental, they had no way of knowing.

This was yet another example of a time when they could use someone like the Doctor. Unfortunately, that already far-reaching chance was looking less and less hopeful.

-:-:-:-

It was getting late, and the DC team would soon be wrapping up another unsuccessful day. Rose maneuvered past the remaining members of the team who were still attempting to calculate why today's most recent attempt of the Dimension Cannon had failed.

Taking a breather from the dismal analyses, she made her way over to the tall glass windows of Torchwood Tower overlooking Canary Wharf. With a pensive gaze, she observed the city below, its occupants ambling to and fro in the evening's bustle as a late-summer workday came to a close. Despite the diversity of the population, there was a similar characteristic to each individual which served to set them apart from her.

They belonged here. She didn't.

It was a feeling that had been almost suffocating during her first months in this world. As time passed and Rose carved out a place for herself within the Torchwood organization, the feeling faded, but was never once extinguished. Moments like this served to stir that sense of displacement.

The sound of an approaching voice brought her mind back to the present.

"Rose?"

She turned to see Pete Tyler walking towards her. She offered an acknowledging smile that didn't reach her eyes, before turning back to gaze outside. He joined her at the windows, looking outward as he spoke.

"You alright?" he asked.

"Never better. Not since bein' here, at least," she replied in a grim tone. Rose drew in a long breath, trying to rein-in the dismal attitude. "Sorry. Just…tell everyone to give me a good kick if I become too much of a misery to be around."

The older man half-smiled. "Nah. Then you'd be too bruised and battered to attend those Vitex functions you love so much."

She snorted. "Thanks."

"Anything I can do to help," he answered back seriously, the lighter tone fading. He turned his head and regarded her for a moment before continuing. "You know, the Cannon wasn't built overnight. It took nearly three years just to get it to this point. Just because we haven't had success yet doesn't mean we won't."

Rose sighed heavily. "I know. It's just that before, we had so much hope. But now…" She shook her head. "If only it looked like it had just a chance of actually getting through."

"It does," he encouraged her. "It might not be capable of penetrating directly through just yet, but it's had an effect. That's something."

"We'd have to increase the strength to get all the way through," Rose concluded, aware of the current determinations being made. She turned to face him. "But we're already operating at the maximum limit for safety. To increase the power output would be dangerous. It could cause the damage we've been trying to avoid with this. You won't risk that. I…I couldn't either."

"There might be another way," he offered optimistically, though both knew no such alternative existed at this point.

Her eyes darkened as the flicker of hope within them dimmed. "And what if there's not? What if this is it? The end of the only chance I had?"

His voice was gentle as he offered the only consolation that could be given. "Then you tried."

Pete placed a hand on her shoulder and gave an affectionate squeeze, then stepped away. Rose turned back to gaze blankly out the window as the light of another day faded.

A universe away, the opposite side of reality's obstinate walls remained unbreached. But from the other side of this omnipotent divide, the effort had not gone unnoticed.