A/N: This is a really old scrapping of mine but I stumbled on it yesterday and got all sentimental over it. I've added the ending to make it a proper incident.

Electro-Magnetic Cloud

Kirk looked about the bridge. Uhura, Scotty then Sulu and Chekov. He flicked his eyes up to the viewscreen again, looking at the nebula. "Spock, how do you read that?" Out of the corner of his eye, he tracked Spock as he moved over from his station, speaker in his ear.

"There appears to be an electro magnetic current, originating from near the centre of the cloud. It appears highly cohesive, and definitely resembles a pattern."
"A life form, Spock? Lieutenant Uhura, are you picking up anything on the communications relay?"
Lieutenant Uhura swung the dials to increase the comm relay's pickup range. "Yes sir, very faint. It resembles a type of code. Running it through the translation matrix now sir..."
"Captain, if there is a new life form here, it would prove an interesting study to report to starfleet."
"You're not half wrong, Spock."
Sulu smirked. "A sentient cloud." He said to Checkov. "Something to write home about."
"It hasn't been determined yet, Lieutenant." Spock countered.

Suddenly there was a surge in the communicator console. Uhura shrieked as a relay sparked with a loud pop. Spock rushed towards her. The console lit up, the computer awash with the electro magnetic surge. It sparked again, just as Spock was attempting to turn it off and he yelped as well. Kirk snapped on the comm switch at his chair. "Bridge, sickbay. Medical emergency!" He snapped it off and rushed over towards the fallen forms of his two officers. He reached the panel beneath the comm station.

Kirk grabbed open the grill and pulled out the power-line input. Unplugged, the station went dark.

Bio-Electric Energy

Kirk turned back to check on Spock and Uhura. They were still breathing.
"Mr Sulu, status of the cloud?"
"Everything's calm over there. The transfer's stopped."
"Chekov." Kirk signalled him over to take up Spock's science console.
"Nothing captain." He said in his Russian voice.

McCoy and Nurse Chapel came up onto the bridge, opening up tricorder and medical kit. Kirk raised his hand before his eyes with a very sudden headache that very nearly knocked him out. McCoy rushed over to Kirk, leaving Christine to the others. "Jim, are you alright?"
"Yeah, don't you worry about me, just see to them."
McCoy turned tricorder to the vicinity of Uhura and Spock. "Jim!" McCoy said in some alarm. "There's a massive energy field here. It's messing with the bio-readouts. Nurse, we've gotta get them out of ... Nurse!"

Switched

Nurse Chapel was fumbling with the hypo at the time he snapped for her attention. She looked up, a strange expression on her face, something between confusion and ... amusement? "Yes, doctor?" Kirk didn't find the situation amusing, and this was the moment he realised his head was starting to throb.
Rather than bothering to finish giving the order, McCoy went to Kirk's chair himself and pressed the intercom, sending for a med team to collect Uhura and Spock's unconscious forms.

"Captain?" Kirk looked back at Chapel and found her studying his composure; apparently he couldn't hide his headache as well as he'd thought. She stood up, carefully and more unsteady than Kirk had ever seen her. He quickly came over to give her a hand and she took his shoulder, like she'd forgotten how to stand up or something. Kirk read from the look of intense concentration on her face that the facts seemed pretty clear to both of them. "We're both feeling a bit under the weather, eh, nurse?"
"Yes, as it would seem, sir."

"Nurse?"

Chapel looked past Kirk to Doctor McCoy's voice but only for a brief moment before Kirk saw her attention turn to the bridge itself ...

Chapel looked down at the unconscious forms, then around the bridge; Sulu at Ops and Chekov at the science station. Kirk followed her gaze and saw Chekov busy getting assessments of the cloud's surge event, Sulu calculating a safer proximity and Scotty was busy making sure no other systems had been affected. Everything was temporarily under control on the bridge.

The turbolift doors opened with the medial back up team.

"I must go to sickbay with them, captain." The nurse stated very careful with each of her words.

Chapel finally turned back to the medical situation and helped McCoy and the others get Spock and Uhura on the stretchers that arrived. Kirk breathed a sigh of relief; she seemed alright after all. He had a headache, and he didn't wish anyone else to be sick.

Kirk turned back, ready to give some more orders to Chekov, but was caught short on Christine's voice.
"There should be a way to..." Chapel was saying, but her voice trailed off before she finished her sentence.
"Nurse!" McCoy snapped at her.
"Yes, doctor. Coming." She made a step to the turbo. Kirk thought it wise to watch her, she seemed earnest but she wasn't quite in full command. As McCoy turned away, she about turned. "Might I suggest, captain, that you run a multi spectrum scan in the b14 quotient sector." She turned and headed into the turbolift behind the rescue team.

Vulcan Stubbornness

As Chapel got into the turbo lift, she stumbled. "Are You alright?" McCoy asked, considering that he hadn't paid much attention to Chapel, and there was clearly something amiss in her facial expression. "Yes, its just these high heels. They are somewhat..."
McCoy was relieved for the moment. "Well, I don't know why you women wear them. Crazy fool things..."
"Please, doctor." There was more than a hint that his nurse's patience had worn thin. "Perhaps we should be determining why the electro magnetic field affected your medical scans on the bridge, and how to reverse the effects on the crew..."

McCoy's stomach inexplicably clenched. "You sound like..."
"Yes, doctor." Came Christine's voice back to him. "It appears there has been some kind of electro magnetic transference side effects."
McCoy shook his head. "And in English, you mean ...?"
Chapel nodded, confirming his dreaded suspicion. "This experience is rather ... curious."

McCoy got Spock and Uhura ... their forms, into sickbay and assessed them. "Life signs are normal." He reported to Kirk, then he hesitated, looking over to Chapel, seated, reviewing her own medical readouts. "But I don't know about... erm..." He shook his head again. "That's not Christine."
"But you're not suggesting it isn't Spock or Uhura, if a life transference has actually occurred? Could it be whatever that was out there that's possessed her?"
McCoy was certain, however. "Oh no, captain. If anything, it'd be hard to miss that Vulcan stubborness, even when separated from his body."

"Thank you, doctor."

McCoy started, he hadn't noticed Chapel's approach, it had been much too quiet. There was still a significant tone of gratiousness to her voice. "They appear to be waking up, doctor. Your expertise appears to be required." So that was why he'd been snuck up on. "Well, why couldn't you tell me from over there? Instead of sneaking up on a man."
There was a bemused expression on Chapel's features. "I have complete confidence in your ability to find a medical solution, doctor."

McCoy shook his head. Kirk had come in with a headache, but he seemed to have picked one up himself.
"I would like to resume my duties on the bridge."
That took the cake. "Your Duties!" McCoy was incredulous but Christine's face looked back at him, tempering him down. "I'd much prefer it if you stayed here, Spock. It might not be healthy for you to get so far from your body. Besides I'd like to do some more tests. I'd like to know why it only affected you three, and why Jim only has a headache."
"Doctor ..." Christine's voice sounded extremely tired and worn. "I am no use here, this is not my field. A better employment of my expertise is on the bridge. Staying here is an ineffectual use of my time."

McCoy looked over to the patients. "I would have to say you're partly right, Spock. they're nowhere near waking up." McCoy narrowed his eyes.
A flash of alarm showed on Chapel's face. "I should know at least that much." She rubbed her head.
McCoy put his hand on Chapel's shoulder. "You just need a break, Spock. Now, do I have to make it an order?"
Chapel frowned at him. "If I am compromised, I will not be very effectual where ever I am."

McCoy stared at her completely astonished. "Why, Spock, I've never heard you say that before."
A flash of indignant anger filled Chapel's features. "Has it never occurred to you, doctor, that quite possibly I have never before had the necessity to say it?" She said curtly and turned to the door, stopped, paused and turned back to face him. There was a look of amusement on her face to replace the anger of moments before. "Perhaps you could assist me with a puzzle, doctor."
"Oh?" McCoy raised an eyebrow. "Me, help you? Why, I'd be delighted, Spock."
"I thought you would be." Chapel's mouth quirked, "whose quarters should I be returning to?"

"Of all the bone-headed-."

"I believe it to be a valid question. My meditation kit is set up in my room, my computer is linked that I may review sensor readouts and I am familiar with the security code."
"Spock!" McCoy took a step forwards, but once again, he was still looking at Nurse Chapel. "I would think the computers were out with your brain turned into a pretzel and don't give me that, that's the honest to god's truth!" He took a breath. "If it's something you really desperately need, I can get that kit for you but as for you walking into your quarters as my nurse, perhaps you should be asking yourself what she would do, what she would think and what people will think of her."

Chapel took a breath. "You have made your point perfectly clear, thank you, doctor. I shall go obtain the security code."
"I am relieved, Spock." McCoy replied. "For once you're actually listening to me."

Chapel turned back, a look of hurt on her face. "Then perhaps it will interest you to learn that I always listen to your arguments, doctor. You are an excellent sparring partner in the field of debate-." Chapel blinked tears back. "I don't believe I have much control over this body. It seems to have its own agenda." She frowned. "And its own list of woes."

"You're human, Spock."

"And I would really hope that I can rely on your expertise to remedy the matter with your usual country styled medicine as expediently as possible." She turned and headed out the door.