This story is a stand alone snippet that jumped into my head at 5am this morning and refused to leave until I wrote it out in full - on my tiny phone. I have no plans to expand on this into a bigger story, but if there is enough interest I might be persuaded.

Gaslighting -
/ˈɡaslʌɪt/
verb
gerund or present participle: gaslighting
manipulate (someone) by psychological means into doubting their own sanity, beliefs or thoughts.
"in the first episode, Karen Valentine is being gaslighted by her husband"

from Wikipedia -
" is a form of psychological abuse in which a victim is manipulated into doubting their own memory, perception, and sanity."

And not just on the victim. It is also used against the victim by pulling others into the gaslighting and using others to unwittingly reinforce the abuse.

If you think you are being gaslighted or think someone close to you is, seek assistance in your local area.

DISCLAIMER - I am not a medical professional at all, in any way - this story is just that. A story written from my understanding of how gaslighting works. All Bullying and Abuse is wrong.

Additional Disclaimer - nothing but this story belongs to me. I receive no monetary compensation or payment, simply the joy of writing.

She watched as the show continued in front of her, her head cocked to the side like a dog studying its master. Her eyes flicked from Sally to Sherlock then to John to see his reaction. A quick scan of the room and she was back to watching the main two combatants.

She hummed, interest plainly clear.
Lestrade glanced up from his desk at the sound.
A quick look at what held her interest and with a shrug, he turned back to his endless paperwork.

She watched as Sally sneered her insults out, her dislike oily and obvious and calculating. She watched as John merely chatted with a female officer while Sherlock studiously ignored Donovan as he muttered, bent over his own files.
Anderson walked in and whispered to Donovan who let out a barking shout of laughter.
'Hear that freak?" Sally taunted while Anderson snickered.

She watched as John glanced at his friend and went back to chatting up the officer. She studied the detective and saw the minute tightening of his fingers on the pen he was holding before visibility relaxing.

Suddenly, with a shout, Sherlock spun around, grabbed his coat and was gone from the room in a flash of pale skin and dark wool. John rolled his eyes, nodded to his new friend and hurried off after the vanished detective.
Anderson and Donovan chatted quiety at her desk, their faces showing their topic of conversation clearly with curled lips and frowned foreheads until a phone call had Anderson scurrying away like a whipped dog.
She watched as Donovan gathered her stuff and also left the room
Finally she looked down at the detective inspector from her seat on the corner of his desk.

In a musing voice, she started to vocalise her thinking out loud.

"I truly do wonder you know" she started with. But the DI was focused on his work. She continued as though he had answered her. "About how people are so interesting. Everyone says that tv is fun or the opera or scuba fishing but I find people to be more fascinating. " Lestrade was humming his reply absent-mindedly, still obviously focussed elsewhere.
"I mean, Sergeant Donovan is obviously up for a promotion and Anderson, well he's just a sycophant who thinks with his dick. Funny that, I would not have pegged him for being any good in the sack but you gotta hand it to the dumb bastard, he must be doing something right to keep at least 2 women happy in the sheets." That caught Lestrade's attention
"What? Argh, what Are you on about?" He asked his nose wrinkling in disgust at the half heard comment.
"Oh Anderson's sex life but that's not what I was actually talking about. No I was referring to Donovan's obvious abuse and molding? Grooming? of Holmes and the complete and utter lack of recognition - no not recognition - care- from anyone. Not a soul gives a shit. Hmmmm" she hummed as she delved into her thoughts, leaving Lestrade gaping at her in confused shock
"Oi, back up and explain that please!" Lestrade finally spat out, angry at the slurs on a good cop and at himself as well.

She looked down, blinking in confusion for a minute as her brain scrambled to rerun the last things her mouth just said.

"Oh." She looked at Lestrade confused. "Why are you pissed? Surely you are trained to spot domestic violence and grooming. I just thought..." she drifted off at the growing anger on the DI's face.
"Seriously? Bugger me Inspector! I've been here all of 2 days and it was clear in the first 20 minutes!"
Lestrade breathed deeply a few time and deliberately placed his pen down calmly.
"Right then, Please enlighten us with your entire 2 days of knowlege of my team." He calmly stated, the sarcasm dripping from the words.

"Oh not just your team, everyone."

She paused to gather her thoughts and gazed out into the now almost empty offices.

"Donovan's up for promotion, that's clear -she reeks of desperation as much as she does of Anderson's foul body spray. To get it she needs something big and juicy I guess. Along comes Holmes. Self identified sociopath, genius level, absolutely little to no inter-personal social skills though he can fake it well enough when he has to. Socially isolated to the point of prisoner in solitary confinement level. Overprotective sibling completes the picture. "
She looks down to see if Lestrade is following and sees he's still frowning in angry confusion. But she can also see that he has an idea of where she is going and the growing green tinge to his skin shows he doesn't like where this train of thought is going.

She changed tack.

"Did You know that within 10 mins of my arrival here with Sherlock, Sally cornered me - yes cornered-" she said at Lestrade's snort of disbelief and raised her eyebrow at him. "Hush, I'm talking" she admonished him and glared until he subsided.
"Now, she cornered me and ordered me to leave Sherlock well alone. Not advised, not a friendly chat as she oh-so-nicely claimed. Ordered me. Informed me that Sherlock didn't HAVE friends, that he was a psychopath and would get me killed, although she actually implied HE would kill me or someone I knew. To bugger off and leave the psycho alone."
She kicked her heels against the desk, and watched as Lestrade sat back in his chair and swallowed hard. Yep, he knew exactly what she was saying. And she continued.
"Then she takes every opportunity to abuse him, knock him. She plants ideas in everyone around him that he is unstable, unsafe and then she feeds that thought, like a vine in a pot. She reminds him over and over of what little worth he has, even though he works harder than anyone else I have ever met, and let me tell you - my entire family are certifiable workaholics! He regularly puts himself in danger to solve things and save people, yet from the second I stepped foot in here, all I have seen and heard from every single person here is how shit he is. Like he is dog crap stuck on your shoe."

She paused to let her words sit between them, like a dismembered head on a platter, foul and shocking.

"Now, who does that? Bullies of course, that goes without saying, but it's deeper than that. It's exactly like that Fetches Case, where the husband convinced everyone that his wife was insane and that she killed the kids until even she believed it."

She looked again at Lestrade and this time caught and kept his gaze.

"You tell me Greg. Who takes a sociopath and systematically and purposely isolates him. Who continually gaslights someone who is already struggling with concepts of societal expectations. Who the fuck does that?"
She could feel herself getting angry now.
"And how the fuck did an entire police force miss this? You have specially trained officers who are supposed to be able to spot and deal with abuse and gaslighting and not one fucking arsehole did anything."
She jumped to her feet and started to stomp around the desks, kicking at chairs and pieces of rubbish.
"I'm horrified. I'm disgusted. I'm out of here. Tell Sherlock I'll only deal with him from now on and not a fucking other soul is permitted to even look my way." She snatched up her cloak and her bag and turned to the stunned and horrified man.
"I'm also devastated. What hope is there when this happens and people allow it. Participate in it." She shook her head, her anger gone and replaced with sorrow.
"Tell Sherlock I'll call him tomorrow." She finished with softly

Lestrade caught up with her at the lifts.

"Wait, look I know it looks bad but..."
"Greg!" She snapped harshly but softened as quickly. " Just .. just don't even…"
He opened his mouth to say something but closed it at her look
Just as the lift doors were opening he finally spoke.
"Okay, I'll get John and Sher.."
Again she cut him off, this time with a harsh chuckle
"John. John John John. There's another whole fucked up thing right there. The man so desperate for the genuis' attention that he allows the abuse so that he has Sherlock all to himself. " she shook her head sadly. "This place is one giant fuckpit with Sherlock as the bitch. I'm surprised he hasn't snapped to be honest."

And the doors slid shut, cutting off the view of the shaken DI as he sinks his face into his hands.