*Hey guys, new Oswin chapter! I wanted to throw a bit of a spanner into the works with this one, as an old acquaintance is back to cause trouble. But it also gives me a chance to show Oswin just softening towards the Doctor a bit, which I think is crucial for this stage of their stage of their relationship. Also, this one's a cliffhanger. I hope you enjoy it! As ever, please please please let me know what you think of it, and thank you so much to everyone who has read, reviewed, followed and favourited! TPD*


Something had changed. Since the sex had started, she had sensed the Doctor was behaving differently, as if some sort of internal conflict was going on. She had tried to find out what was going on in his head and if it had anything to do with their sleeping together, but he insisted that it was just an adjustment period. Within a couple of months, he seemed to have settled down and was back to his usual, cheerful self. Oswin knew that there were things that he was keeping from her, there always was. But he seemed to be okay with their arrangement, whatever their arrangement had become. Oswin thought that the technical term was friends with benefits, but frankly, it didn't bother her one jot. She cared about the Doctor and they were having sex, that was all there was to it.

Oswin was worried about him nevertheless, but that was just the nature of their relationship. It seemed to her that now that things had settled down, there was a chance that he would stop throwing himself into life threatening situations. If anything it was the opposite. She half-wondered if the sex meant that he was craving adrenaline. She wouldn't put it past him, as much as he didn't seem like the adrenaline junky type.

One morning, a couple of months after the sex began, about nine months since she'd started travelling with him, he seemed incredibly subdued. Oswin strolled into the console room, wearing a dark blue skirt and blouse and tights and rested herself on the console itself, waiting for him to acknowledge her. But he didn't. He just kept staring at the console, as if deep in telepathic conversation with it. She cleared her throat and he looked sharply at her, a smile appearing for less than a second on his face.

"Are you alright Chin?" she gave him a bright smile and he turned away from her, as if the simple sight of her was confusing him. "Chin?" Oswin's voice went into caring mode. She hated having to be gentle, but sometimes it was the only way to get through to him.

"I'm fine," he muttered. "It's just…we're going somewhere and…"

"And what?" Oswin frowned. "Where are we going?"

"River Song," he said suddenly. "She contacted me. She needs my help…"

"Only you didn't want to see her again," Oswin finished, putting two and two together. "Oh god Doctor, I'm so sorry. Is there any way you can get out of it?"

He grimaced. "It's not about not going. If I don't go, she'll probably die and it'll create time ripples so powerful…"

"Ahhh timelines, goddit," Oswin nodded. She walked over to him and pulled him into a rare hug, he looked like he needed it. He clung to her gratefully. "Are you going to be okay with this, seeing River I mean? All those memories…"

"I can handle memories," he sighed. "I'm just not sure I can handle River, it's been a while. Six months since…" He didn't say New York but Oswin knew he was thinking it. "Anyway, are you going to be okay with meeting River?" he asked quickly. "Would you rather stay in the TARDIS?"

"What, because we're banging?" Oswin snorted. "Relax Chin; I'm not the jealous type. Whatever's gone on between you and River is between you and River, I couldn't care less. I only want to make sure that you're alright."

"I didn't realise that you cared so much Soufflé Girl," he chuckled.

"Shut up!" Oswin blushed. "Of course I care about you Doctor, I love you to bits. You saved my life; you've given me everything I could ever have wanted, the entire universe. You're a great friend…" she paused. "You're the best friend that I've ever had." She hugged him again, this time for her own benefit. She rarely ever let herself feel emotional, but she had to admit that she owed the Doctor everything and she truly did care about him, more than anything. She broke the hug eventually and punched him on the arm to defuse the tension. "So, where are we going to chase after River Song?" she asked playfully.

The Doctor was giving her a strange look, one that she couldn't place. He suddenly seemed to snap to attention and grinned at her. "Absolutely no idea, she sent the co-ordinates to my psychic paper. Want to find out?"

"Always," Oswin's eyes lit up at the idea of a venture into the unknown. She grabbed and flipped a couple of switches for him as he tried to stretch around the console. The look on his face whenever she helped him fly the TARDIS was nothing short of priceless, pure shock, before he remembered her ability and then he would glow with pride and nod appreciatively, trying to pass it off as nothing. Oswin was never fussed about his approval, but nevertheless, she still got a kick out of it. It was impossible not to in all honesty. The TARDIS landed abruptly and Oswin staggered back, managing to retain her balance. The Doctor wasn't so lucky and he tumbled to the floor. The cackling that usually went with it was gone and he picked himself up. There was a serious look on his face and when Oswin walked to the doors, she felt his hand lace hers. It was another odd gesture, one that conveyed a level of dependence and emotion that Oswin was not comfortable with. But he needed her to be, so she accepted the hand, cold against hers and he shot her an uneven smile. Then they stepped out of the TARDIS.

The land they had stepped into was rich with greenery. The heat hit Oswin in a wave and she was already sweating and wished she could have changed to shorts. The Doctor let go of her hand and stripped off his jacket, throwing it back into the TARDIS. Oswin did likewise with her cardigan, throwing it to him and nodding appreciatively as he disappeared back into the box. She also tied her hair up in order to expose her neck to the minimalistic breeze that was licking her arms. There were footsteps crunching through the undergrowth and Oswin whirled around to see a woman dressed in khaki shorts and a top, her thick, curly hair all piled on top of her head. She was older than Oswin had expected, but no less attractive. Oswin absorbed the woman and offered out a hand to shake, giving River Song her brightest smile, the smile that made the Doctor putty in her hands.

"Oswin Oswald," she greeted cheerfully. "I picked up this one a while back," she shot a thumb backwards into the TARDIS. "You must be River Song."

"Professor River Song," River corrected with a smile. "I'm an archaeologist. The Doctor and I have a…complicated history. Time streams and all that, not sure how much I should say."

"You're married," Oswin said before she could stop herself. "I think. Sort of. Complicated. I think he's far along in the time stream. Seeing as you're a Professor, guessing you are too?"

"Smart girl," River smirked. "Where are Amy and Rory? Off playing happy families?"

Oswin tried not to flinch at the mention of the Ponds and instead nodded, not trusting herself to speak. Luckily, she didn't have to, because the Doctor emerged from the TARDIS a moment later, hurling Oswin some sun cream. Oswin lathered up her arms and face, not wanting to burn. She was already a wonderful shade of nut brown from the week or so they'd spent in the desert recently, a sunbathing trip gone wrong. She hadn't been able to move for almost a day, as her skin had been red raw. The Doctor stared at River briefly, before forcing a smile onto his face.

"River," he greeted nervously. River raised an eyebrow. "Good to see you."

"Is it?" she asked with a smirk. "Then why do you look like you'd rather not be here?" The Doctor didn't respond. "Anyway sweetie, I didn't bring you all the way out here just to gossip. I need your help, as ever. We're not on Earth, obviously." Oswin had no idea why that was obvious, she'd been working on the assumption that they were in the Amazon. "The temple just over the way is uninhabited. That we know of."

"That's the worst kind of temple," he muttered. "How bad are we talking?"

"That's the point," River chuckled. "We've got no idea. Could be genuinely uninhabited, could be about as bad as it could get. Most likely somewhere in the middle. Either way, I thought it would be better to call you in before we went in to excavate. I have a team of twenty men, but I figured you and I could check it out first, make sure it's safe. Oswin, I take it you're joining us?"

"Wouldn't miss it for the world," Oswin replied with a tight smile. She wanted to like River, but she could see how on edge the Doctor was around her and it made Oswin annoyed. If she didn't know any better, she'd say that she was feeling protective. "Lead the way Prof."

Calling River 'Prof' earned her an incredulous look from River and the cheekiest grin she had ever seen the Doctor make. They traipsed through the jungle for about ten minutes and Oswin was sweating buckets by the time that they reached the temple. River was slightly ahead of them, as the Doctor was deliberately hanging back, presumably so that River wouldn't engage him in conversation.

"How're you hanging in there?" Oswin whispered, keeping an eye on River to make sure that she wasn't eavesdropping on their conversation. "And what do you expect to find in that temple? River wouldn't call you in unless it was bad, right?"

"Probably not," he admitted. "But I can never tell with River. Still, if her gut tells her that there's something in there that meant she had to call me in, then chances are, we're walking right into a death trap. I'm glad to be honest, it will give me something else to focus on. Something besides the good Professor," he sighed. He, like Oswin, was watching River Song like a hawk. Oswin could see the look in his eyes. He was torn. Part of him wanted to go to her and rekindle whatever it was they had had. The other part wanted him to stay put.

They crossed the ridge and came to a giant clearing. The temple looked very small, only a couple of stories high. Oswin frowned at the sight of it, it was obviously run down. It wouldn't take much exploration. There was a set of twenty men, one or two of them armed, roaming around the front of the clearing. They converged when River arrived, and she nodded to one or two of them.

"The majority of the temple is underground," she explained and Oswin twigged. "There are tunnels underneath there that could run for miles. It certainly goes down quite far. It'll be pitch black down there, but we've got torches."

"Yay for torches," Oswin muttered under her breath and the Doctor smirked at this.

"The men are going to stay out here," River continued. "We should be in radio contact with them the entire time, but it could get deep down there, so I wouldn't be surprised if you needed to boost the signal sweetie," she said to the Doctor. He nodded at that. River seemed to pause and then looked oddly at Oswin. "Can you give us a minute?" she asked.

Oswin raised an eyebrow but didn't say anything. She shot the Doctor a look and the Doctor took a moment to chew on his lip before nodding. Oswin took a few steps back, trying to ignore the awkward looks that the archaeologists were shooting her. They didn't know what to do in this situation any more than she did and that made Oswin nervous. After a minute or so, the Doctor returned to her side and they were following River into the temple.

"What was that about?" Oswin asked in an undertone.

"Nothing important," he assured her. "River wondered if something was going on between us, and if that was why I was being so awkward around her, unusually so." He sounded irritated and Oswin put it down to the fact that he couldn't tell River the truth.

"What did you tell her?" Oswin's curiosity had been peaked. It would be interesting to see how the Doctor had defined the parameters of their relationship.

"I told her that we were sleeping together, but just friends and that our relationship had no bearing on my attitude towards River. It merely happened that it had been a long time since I had seen her and that I had considered it unlikely that I would see her again. 90% of the truth, just not the bit that's really…"

"Really bothering you," Oswin mused. "Sorry Chin. I know this must be hard for you."

He wanted to reply, but River had dropped in alongside them. The temple they were entering was full of light, at least on the surface, but there was nothing interesting to be found on this level.

"My people have already scouted out this level," River informed them. "There's nothing of note. Not for you anyway, plenty of fascinating archaeological discoveries, but I won't bore you with the details. Anyway, the entrance to the caves is here," she ushered them to a small hole in the ground. River went in first, followed by Oswin and finally, having shot one more furtive glance around, the Doctor. Oswin checked he was following them as they kept low, walking down a small passage into a cavern. It stank of death and decay and Oswin felt ill just being down there. There were bones and rocks in the cavern, which wasn't that big, but big enough that they could stand. River had a map of the tunnels at her disposal and guided them down a side-tunnel, declaring that whatever tombs were down here, they were in that direction.

"So the tombs are whatever lives down here?" Oswin whispered to him. "Or what died down here?"

"One of them," he acknowledged. "We'll find out which one soon enough. What planet is this River?" he called to her and she shot him a look back. "River…" the Doctor frowned.

"I don't know!" she shouted back. "All I know is that we're in the Cletaria Nebula, designation Alpha Gamma Epilson, planet recording 563. Ringing any bells?"

"Give me a minute," he muttered. "It'll be somewhere in my brain. Oswin, can you remember the number for me and tell me again when I ask?"

"Sure," Oswin rolled her eyes. They climbed deeper into the cavern and the Doctor was deep in thought. They entered the catacombs and River's torch started flickering. She frowned and bashed it back into life. It was very cold and eerie and Oswin looked around. There was one wall, with hundreds of openings. They reached a set of steps and looked down. It looked like it went down for miles, with holes jutting out of the walls the entire way down.

"What was the number Oswin," the Doctor asked gently, as River went over to examine one of the holes in the wall.

"563," she recited. "Is it important? What planet are we on?"

"Get back," he said sharply. "River get back!"

"Why?" she frowned. "What's wrong, Doctor what planet are we on?"

"Tylectia," he said. "The name won't mean anything to you. It shouldn't mean anything to you. Because here's the thing. It's uninhabited." River froze. Oswin looked at him in confusion. "Nothing lives here," he continued. "At least, nothing should live. Nothing natural should be here anyway…"

Oswin asked the question that they were all thinking. "So how can there be tombs then?"

At this point, something shot out of the hole River was stood next to and pulled her in. River barely had time to scream…