Spoilers: United, The Aenar, Affliction, Divergence and most of Season Three.

AN: This part is set after Affliction and during Divergence.

When the call came through from Enterprise, Trip had been down in Engineering working on the maintenance schedule for Columbia. At the moment he had no idea who would work best with whom so he'd just have to put some teams together and see how they did. He would fine tune it later when he had a better idea of everyone's strengths.

"Commander Tucker to the Bridge," came the call and he immediately had a feeling that something bad was happening. He dropped the padd he was working on and ran for the bridge. He arrived to see Captain Archer on the view screen and Captain Hernandez asking for a rendezvous time with Enterprise from her helmsman.

"We can be with them in thirty minutes, Ma'am," said the helmsman.

"What's the problem, Captain?" asked Trip. He was unsure which Captain would give him an answer.

Archer spoke from the view screen. "We've been trying to track Phlox down and had some trouble with the Klingons. They boarded Enterprise and altered our Engineering subroutines. They created a malfunction in the intermix chamber, plasma pressure is rising and the anti-matter flow regulators are locked open," said Archer. "If we drop below warp five then the reactor's going to explode. We can't maintain warp five point two forever and we've got less than an hour before the reactor breaches. We're out of options and I was hoping that as the man who knows Enterprise's warp engine best you might have something that we haven't thought of."

"Damn, Captain, you sure know how to put a man on the spot," said Trip. He was already thinking frantically. There was only one way to deal with this in the time available that he could think of. "You need to restore the subroutines, but to do that you have to drop out of warp and if you do that then the reactor will breach. I can think of one way of doing it and it isn't going to be pretty. The only problem is that I'm on the wrong ship, I need to be over there."

"You can't talk us through it?" said Archer.

"I could but I'm not sure we've got the time, or even if Kelby's up to it. To do what I'm planning you'd have to know the engine like the back of your hand and Kelby hasn't even been there a week."

"That's all well and good, gentlemen," said Hernandez, "but we can't transport you over while Enterprise is at warp and there's no way for us to dock."

"There's another way of getting me over there. Lieutenant Reed and I once discussed ship to ship transfers via tether at warp speed. He was part of a Security team that carried one out and knows the procedures. I don't think its ever been done at warp five but it can't be that different from lower speeds."

"I'll talk to Malcolm," said Archer, a look passing across his face that Trip nearly missed but couldn't identify. "We may have no choice but to try it. I'll get back to you in five minutes. Archer out."

The screen went blank and Hernandez turned to her Chief Engineer. "You do know what you're doing, don't you?"

"I've got a good idea Ma'am," replied Trip.

"What you're proposing is incredibly dangerous. If the tether were to snap while you're making your way across then you'd be thrown out into space at warp five. We'd most likely never find you again and the speed alone could kill you. That's before we even get into the situation that you'd be going into."

"I understand the risks, Ma'am, but there's eighty-seven people on Enterprise that are going to die unless I do this," said Trip. Those eighty-seven people included some very good friends. Those eighty-seven people included T'Pol and he'd give his life for hers alone without a second thought. The realisation that he really meant that shook him a little. No matter how hard he tried to leave Enterprise it seemed that fate wanted him back there. It looked like he was going to have to deal with working in close proximity to T'Pol one last time before he could move on. Unless of course this was the last time he worked with her, full stop.

"Just checking, Commander," said Hernandez. "Get yourself down to the launch bay and get your EVA suit on. I have a feeling that your former CO will be in touch very shortly to let us know that your expertise is needed."

"Yes, Ma'am," replied Trip, exiting the bridge as quickly as he could.

T'Pol watched as the two ships came within 50 metres of one another. Outwardly she was completely calm as the two warp fields collided, before she made her way down to Engineering. She readied everything, all the time knowing that Trip was now on his way, suspended between the two ships on only a thin cable. A shudder let her know that something was wrong and the warp field was fluctuating again. She heard Travis saying that the distance between them and Columbia was increasing and did her best to divert power to stabilise the warp field so that they could maintain position.

She couldn't deny the worry she felt for Trip as he traversed the void between the two ships and she wished it was her at the other end of the tether waiting for him. She knew that if they couldn't get the warp field under control then it could very well be Trip's death. She tried diverting more power but it made no difference the problem was not how much power the warp field had but the instability being caused within it.

In the back of her mind she could feel a mirror of the fear that she knew Trip was experiencing. He was trying to be brave and concentrate on the tether but it was hard for him not to feel alone out among the stars. Suddenly with shock she realised that this wasn't just her imagining the feelings that he might be having, she was actually having them. Trip appearing in her meditation suddenly made a lot of sense. She knew that now was not the time to deal with this, so instead she concentrated on feeding back to Trip that he was not alone, reassuring him that he would make it. He doubted that he would even realise where the reassurance that she was sending him was coming from, but it would be there none the less.

"T'Pol to the bridge, it's not working the field is still fluctuating." Trip was depending on her and she was failing him. She kept trying while she waited anxiously to hear the news that Trip had made it safely to Enterprise.

Trip had never been so nervous about a space walk. He was trying to think of it like that, just another routine space walk like hundreds of others that he'd done. Malcolm was doing the hard part, firing the tether and monitoring the tension in the line.

The tether zoomed past Trip. "Nice shooting, Malcolm." He gave the tether one last look before he attached his harness to the line. No going back now. "Tucker to Captain Hernandez, I'm heading out."

"Quick as you can Commander," replied Hernandez as another shudder shook Columbia, passed on via Enterprise's deteriorating warp field.

Trip took a deep breath and he began lowering himself towards Enterprise. He reached the halfway point and took a second to look at the stars and suddenly he felt very alone and afraid. Fear gripped him for just a second before he suddenly had a picture of T'Pol calling him towards Enterprise and telling him that everything was going to be fine. He completed his turn over at the mid point and began to move "upwards", although it was all relative to the position of the ships, there was no real up or down in space.

"You're doing fine, Trip," said Reed but Trip could hear the tension in his voice and knew not everything was fine. Reed was concerned about something but he wasn't going to burden Trip with any more problems while he was dangling on the end of a cable. Trip could feel more shudders move down through the line.

"Don't mean to be a pest, but could someone tell me what's going on?"

"You're almost here, Trip, keep going," said Reed in the same strained tone of voice. Things were not good. Again suddenly T'Pol's image was in his mind telling him not to worry and to move more quickly. He could almost see the warp engine controls that she seemed to be looking at. If those readings were right and not just his imagination then things were worse than he'd thought. He concentrated on the tether again and began to move faster.

Then suddenly Reed was shouting "The tether's at its limit. Hurry up!"

He could feel the tether give slightly as he moved up, it was being pulled away from its mount by the force being exerted between the two ships. Then he could see Malcolm waiting for him and he put on a final burst of speed. He made it to level with the deck and Malcolm was detaching him and grabbing onto him at the same time, working as quickly as he could. They were both aware of the fact that if the tether went now, while he was still attached to the line, it would take Trip with it. Malcolm finally had the harness unclipped and Trip noticed him look up before he was suddenly being pushed out of the way as the tether mount came crashing down.

Trip breathed a sigh of relief. "Permission to come aboard?"

Malcolm just gave him one of his looks, half way between relief and indulgence at the joke, before moving to the controls to close the bay doors and let the Captain know that he was on board. Trip then explained his full plan to the Captain. It sounded impossible even to him, but he knew this ship and her engine, he was confident that it could be done.

Reed and he climbed out of their EVA suits as quickly as they could. Reed handed Trip a spare uniform in his size and momentarily Trip felt pleased that the uniform bore the shoulder patch of Enterprise. It made it almost seem as if he was being welcomed back home. He wished that he really was back for good and the Columbia shoulder patch he was becoming accustomed to wearing just reminded him that Enterprise wasn't his ship any more.

When they left the shuttle bay, Trip was surprised to see two MACO guards waiting for them. When Reed explained, or rather didn't explain, why they were there, he was even more surprised.

"I leave the ship for one week and the whole place goes to hell in hand basket," he muttered to himself as strode down the corridor to engineering. Of course the first person that he saw when he entered Engineering was T'Pol.

"Fancy meeting you here," he said as he went to get the tools he'd need for what he was about to do. "Intermix pressure?"

"Fifteen twenty seven," replied T'Pol, looking about as stressed as she ever did. He got the impression that she was not happy to see him. And that pressure reading was way too high.

"Field variance?"

"Eighty seven milli-cochranes."

Ouch, thought Trip. This was all very bad. "Someone hasn't been taking very good care of my engine."

"Speak with the Klingons," retorted T'Pol. Trip was sure he was right now, she was definitely not pleased to see him. He turned to start on the cold start process.

"What are you doing?" asked T'Pol.

"You might want to take notes. I'm about to perform a manual shut down and restart in less than two minutes." He climbed onto the top of the warp core, remembering that the last time he'd had to do something like this, he'd ended up in sick bay.

"That's not possible."

T'Pol was always the optimist, as usual, thought Trip sarcastically. "Watch me."

After that everything was a blur of activity as they merged warp fields with Columbia and Trip battled to shut everything down and then bring it back up again before Columbia's warp field failed. Even though he was dealing with a crisis, he felt that this was right. He was giving orders to his crew again and fixing his engine. When he pushed the final relay back home he knew that it had worked before the power even came back, that was how well he knew this engine.

"Engineering to bridge, subroutines have been purged," said T'Pol. Even she sounded relieved.

Trip let out a sigh of relief. He caught T'Pol's eye for just a second and he was sure that he saw something there that hadn't been there before. He didn't have time to think about it further though, the Captain was congratulating him and he needed to make sure that Enterprise would continue to be okay. He looked back towards T'Pol and felt something that he hadn't believed to be possible. He felt happy and he was almost certain that she was happy to have him back too, except that couldn't possibly be true. Especially after the welcome that she'd given him.

He needed to find some way to stay on Enterprise a bit longer. He had to work out if what he thought he'd seen in T'Pol was actually there. He wondered if Kelby would mind a little help. After all, those Klingon subroutines could have done who knows what to the warp engine.

Archer lay on his biobed feeling a little sorry for himself. The Klingon virus had been hard on his body and he wasn't getting any younger. He had been lying there trying to think of a way that he could persuade Trip to stay on Enterprise. It was as if he'd been given a second chance with his Chief Engineer and he intended on grabbing it with both hands. If Trip had been on Enterprise during their most recent engineering crisis then things might not have become as desperate as they had. He'd already spoken to Captain Hernandez about his plan and assuming that Trip agreed, she was amenable to an extended leave of absence for her Chief Engineer. Archer suspected that she already knew that Trip would probably end up coming back to Enterprise. Whatever had hurt him enough to leave needed to be dealt with but he'd seemed a lot happier when he'd last seen him. Archer wondered what had changed. Maybe he'd just needed a bit of distance.

Trip wandered into sick bay. "Hey Captain, how're you feeling?"

"Better," said Archer simply.

"Good," said Trip. "I thought I should bring you down the repair schedule. It could have a been a lot worse, everything's minor, there's just a lot of it."

"Actually, I was hoping I could persuade you to stay a little longer. We're short handed and we need to get moving again."

"I don't know if Captain Hernandez will be happy with you stealing her Chief Engineer from her. We're short handed on Columbia too you know."

"But at the moment Columbia's in better shape than we are. She's already agreed, Trip. It's up to you, if you want to stay on a little longer, I'd be glad to have you."

"You know, I was actually coming down here to ask if you'd mind taking in a stray Chief Engineer for a bit. I thought Kelby could do with a hand."

"Then it's all settled."

Archer smiled at his former Chief Engineer and Trip returned it. One of Phlox's assistants came over to the Captain's biobed to perform the final set of scans before he was discharged and Trip stood waiting while they were completed. At that moment T'Pol and Hernandez decided to join them and Archer noted the way that Trip's eyes lit up when he saw T'Pol. The final piece of the puzzle clicked into place.

I may be slow, thought Archer, but I get there in the end. Mystery solved. Sparks had been flying for years between his Science Officer and his Chief Engineer, he wondered why he hadn't spotted their obvious attraction sooner. The question was could the two of them sort it out before Trip transferred back to Columbia. Starfleet didn't like playing musical chairs with its officers, but now Trip was back on Enterprise it would definitely be easier to keep him here. Plus if Archer had anything to do with it, he'd be making sure that Trip didn't even think about leaving again.