Another Detective ?! (Mycroftxreader)

Chapter 1 ~I 'll take that as a "yes"~

The first day at Scotland Yard... great... I've already heard of the arrogance and the incompetence of the people working there. So my hopes aren't very high.
Walking into the building, I headed straight to the reception desk.
"Hello, How can I help you?" the woman behind the desk asked.
"I need to see Detective inspector Lestrade," I replied simply.
"He's out on a case, but if you tell me you're name. I can talk to him and get an appointment," she told me.
"Why don't you just give me those files you wanted to bring him anyways and I'll head to the crime scene he's recently at?," I said, giving her a questioning look while pointing at the files on her desk.
"You can't just go to a crime scene. This is police business!" she exclaimed, getting annoyed of me.
"So I'm afraid it's my business," I responded dryly.
"Excuse me?! Who are you anyway?" she almost spat.
"Detective (y|n) (y|l|n)," I replyed blackly.
"Oh...," was all she got out.
"Where?," I questioned.
As she couldn't talk she just handed me a tiny piece of paper, on which the address was written.
I grabbed it and also the files from right under her nose, spun on my heels and walked out of the police station. I waved for a cab, making one pull over immediately.
"Where to? Miss? ," the cabby asked.
I just handed him the piece of paper, I received a few seconds ago.
By the time we arrived, I almost jumped out of the cab. I gave him the already counted cash and walked right to the crime scene tape, lifting it slightly to get through.
"Stop right there!" a woman yelled at me.
I rolled my eyes. She was obviously a Sargent. I just pressed the files against her chest and headed to the house, my long, black coat billowing behind me.
I walked right through all of the police officers and a not too good looking forensic.
"Wait you can't pass," someone behind me screamed.
"I can and I will," I responded coldly, holding my badge up while walking and not turning my head.
"But the Detective Inspector said..."
I just kept walking.
I climbed up the stairs taking two steps at once. The door on top of the stairs was closed and there where people talking behind it.
I just opened it up, not caring about the impression, I would make on my new Boss. As I busted into the room, my head immediately captured the scene in front of my eyes and analyzed it. There was a woman dressed all pink laying on the floor dead, next to her was a message she scratched into the wooden floor, using her nails, dying "RACHE...". A man in a dark coat similar to mine, with the same leather gloves, was standing in front of her. His head was turned towards Lestrad, standing in front of me. Next, to Lestard, there was a shorter man, judged by his appearance an army doctor. The scene started moving again. The guy in the dark coat said, "All of her jewelry was cleaned regularly, except for her ring...,"
"She must have been naughty," I thought out loud, what I concluded from those few words.
Lestrade turned on his heels facing me shocked and confused.
"Detective (y|l|n)?!"
"Exactly! I did not expect you to recognize me," I told him a bit sarcastically proud.
"Detective?," the army Doctor asked.
"Yes, Doctor?," I smirked. He gave me a confused then amazing look.
"Watson. Dr. John Watson," he exclaimed reaching his hand out for me to shake it, which I did.
"Detective (y|n) (y|l|n)"
"This is Sherlock Holmes, our consulting Detective," Lestrade introduced the man, with the high cheekbones.
"We should probably get back to the dead woman," I announced, kneeling next to her.
"So she was lefthanded, worked as a moderator, was traveling a lot, was cheating on her husband, wanted to write" RACHEL" down before she died and if we check the weather map we'll find out in a second where she came from...," I deduced.
"Cardiff, she also had a suitcase, she only wanted to stay one night..., " the consulting Detective added.
"I swear if you're only making that up right now..., " Lestrade grumbled.
"He's not it's obvious, " I interrupted.
Holmes explained the deductions and Lestrade nodded in amazement.
"Well fine, but what am I doing here?" doctor Watson asked. "Helping me make a point," the man with the bright blue eyes replied.
"I'm supposed to be helping you pay the rent," the shorter one concluded. So they were obviously living together...
Holmes looked at him pulling his eyebrows together.
"Yeah well this is more fun," he meant.
"Fun? There's a woman lying dead," Watson responded shocked.
"Perfectly sound analysis but I was hoping you'd go deeper," the Detective announced looking at him.
"She probably choked to death while seizing," I cut in, getting up on my feet.
"This is exactly what I was about to say...," The grey-headed doctor meant nodding.
"Where is her suitcase?," I asked turning to Lestrade.
"Which suitcase? ," the D. I. asked confused.
"The pink one she carried," Holmes sad
"What happened to it, did she eat it?" he asked sarcastically.
"He must have kept it. Or she forgot it in his car," I exclaimed storming out of the building.
I ran across the crime scene, checking every possible location of the suitcase on my mind map.
3 alleys and dirty gloves later I found the suitcase in a garbage container. As I walked out of the alley I recognized Holmes standing in a container.
"Got it," I told him while passing him.
He got out of the container and walked up to me.
"I need it!" he exclaimed. I pushed it on his chest, as I did it with the files and that Sargent earlier.
"I know and as I am obliged to give all of the evidence I find to my Boss, which would be stupid 'cause he'll give it to his incompetent forensic, I never found this suitcase. I believe you' ll facilitate me to examine it later one," I nodded. The Detective nodded.
"The the address is 221B Baker Street, " he said as we got out of the alley and our ways parted.
"I'll take that as a "yes", I mumbled to myself walking back to my flat.

picture sources:
https://www.flickr.com/photos/timarai/5278411855
https://blamayertv.wordpress.com/2012/05/20/sherlock-1-01-ein-fall-von-pink-gedankenduell/
https://m.youtube.com/watch?v=7HMBG2DA97M
https://en.m.wikipedia.org/wiki/Scotland_Yard