This is my first M rated story and my first Lost in Space story so please don't be too hard on me. I've never seen a Don/Smith story before so I hope y'all like it.

Don groaned in exasperation as he saw that, once again, Doctor Smith was lazing around in the sun instead of pulling his own weight. "Hey! Smith, why don't you get off your lazy ass and do some work around here!" he snapped.

"Major, I assure you, it is not that I am lazy. It is simply that I have a delicate back," came the doctor's automatic response.

"I'll give you a delicate back," Don muttered under his breath, trying to compose himself. He didn't want to kill the annoying man… at least not in front of the children.

Putting down the equipment he had been carrying, Don stormed over to Smith's chair and pulled him up harshly by the arm, earning a startled yelp from the doctor. "If your back is too 'delicate' to carry equipment, then maybe you can help get things straightened up inside. I'm not going to let you just lounge around in the sun all day and then expect to be fed and protected every night!" Before Smith had the chance to think of a smart-ass reply, Don dragged him into the Jupiter II.

"Major West, I assure you, I am more than capable of walking on my own," said Smith, narrowing his eyes as Don released his grip on his wrist.

"Really? By the way you sit around here all day I never would have known! Now, the lightbulb in that consul over there went out, do you think you can handle fixing it?" asked Don.

"Never fear, Smith is here," the doctor smirked cockily.

"Alright then," said Don. "Change the lightbulb."

Doctor Smith looked around the bridge of the Jupiter II nervously for a few seconds; how was he supposed to do anything with Don watching him like that? Besides, he didn't know how to change the lightbulb without electrocuting himself! "Well, perhaps I should get Will to help me; shame to waste the boy's talents. William, my dear boy! Get in here and help me!" he called outside.

The pilot growled under his breath and just as he was about to lash out at Doctor Smith, Will, the boy-genius, came happily bounding inside, like an obedient puppy. "Yes, Doctor Smith?" he asked.

Don answered instead. "Nothing, Will. He doesn't need you. Go outside and play with your sister."

Will shrugged. "Alright, Don. See you later, Doctor Smith."

Then once he was sure the boy was out of earshot, Don let his anger resurface and took an intimidating step towards Smith. He noted how the doctor backed away and began to tremble. "That's it, Smith. I'm done with you. I'm sick and tired of dealing with your antics every god damn day! You're always whining and complaining about how you want to go home! Well, newsflash, buddy, you're not the only one who wants off this planet! We all want to go home! So I suggest you quit complaining about it, get off your ass, and start actually doing something about it!"

By this point, Don had backed Smith almost completely into the consul and he was sure that he had won. But of course, Smith just couldn't let it end at that. Timidly, he lifted up one finger in protest, "But, Major, my back…"

And that was the final straw for Major Don West. "I don't give a damn about your fucking back! You… you…" He was so angry he didn't even know what to do. He wanted to punch Smith, kick him, shoot him, throttle him, anything! Without thinking, Don surged forward to do something to hurt Smith… and ended up kissing the man.

Violently and forcefully Don smashed his lips into Smith's. Immediately the doctor's eyes widened to the size of dinner plates and he froze in place as Don viciously attacked his lips. With rage and adrenaline surging through his veins, Don continued the venomous kiss. He didn't know what else he could do to get rid of all of his pent up frustration, anger, and lust.

As Doctor Smith felt Don force his tongue into his mouth, he relaxed slightly and allowed the young man entrance. He had absolutely no idea what was going on but he thought he might like it… Teeth clashed painfully as tongues battled for dominance inside the arena of their mouths and Don felt himself begin to get hard.

Instinctively he began to rut against Smith's thigh and broke off the kiss with a moan. "Aw fuck. I'm so wound up," he breathed. "Haven't gotten laid since the start of this mission."

Smith had to raise an eyebrow at that. "Really? What about Judy?" he asked, and made no effort to stop Don from humping his leg. The doctor was already pretty hard himself.

Don laughed scornfully. "Judy? She's way too much of a prude to do anything with me. The most I could get her to do was kiss me, and not even with tongue!"

Don thrust particularly hard against Smith, causing the doctor to buck his hips forward and moan. "If you think you've got it bad, Major, I haven't had sex in three years."

"So you haven't been molesting the children behind our backs?" Don joked darkly.

Doctor Smith stopped thrusting and pulled back instantly to gape at Don with an expression of disgust. "Major West! I am appalled that you would even suggest that! You know I care about those children as dearly as if they were my own!"

Don sighed; maybe that one was a bit too far over the line. "Shit, I'm sorry. I'll admit, that was a low blow."

At the sound of the word 'blow' coupled with the connotations of 'low', Smith was rock hard again. "Speaking of low blows," he smirked suggestively, "One would not go unappreciated right about now…"

Don glared at him. "Not on your life, Doc. Just be thankful that this is even happening."

Smith nodded and decided to keep quiet. He didn't want his big mouth to interfere with what might be his only chance at ever having sex again. The two continued to thrust and rub against each other, suppressing soft grunts and moans. Smith opened his eyes and took a moment to visually appreciate the young man thrusting against him. While Don wasn't usually his type, the doctor had to admit that the pilot was quite handsome, especially with his face contorted in pleasure. Smith wondered how this had even happened; he had never pegged Don as a gay man. But then again, maybe he wasn't; maybe he was just desperately horny.

Deciding to be bold, Smith moved his hands from the consul to Don's hips. Thankfully the pilot didn't seem to mind and just thrust faster. Smith picked up the pace as well and could tell that he was getting close. "Major… I cannot last much longer," he warned.

"We didn't even get to the bedroom," said Don breathlessly, tightening his grip on Smith's hips. And that was enough for the older doctor; he shuddered violently and came hard in his pants. Seeing Smith reach his orgasm was enough to push Don over the edge as well; he came gasping and collapsing against Smith. "Fuck," he breathed out as his heart rate returned to normal.

"Fuck indeed," agreed Smith, equally as breathless.

Don stepped back from the doctor, shocked at what had just transpired between them. He took in the sight of Doctor Smith; breathing ragged, pupils dilated, wet stain on his pants, confused and overwhelmed. Don just couldn't believe that he had caused the other man to be in such a state.

"We never speak of this. This never happened. Agreed?" Don ordered sternly.

"What never happened, Major?" asked Smith with a sly smile.

"Exactly," said Don, and he stormed off to his quarters to go change his pants.

Reviews are most appreciated :)