I mentioned in the TV Show review on the first Sherlock episode that I have a couple of theories on Mary Morstan. They began to develop after I first saw the end of the episode with and I saw a screen shot of Sherlocks deductions of Mary. 
All the words that stood out to me were the ones that are circled in red.
- Guardian
- Disillusioned
- Clever
- Secret
- Liar
Now right away, yes secret tattoo can be the phrase, but the fact that the rest of the time secret isn’t near tattoo leads me to believe there is more to Mary than meets the eye. These phrases made me reanalyze everything about the series.
I first watched Sherlocks reaction to these deductions. 
Between Sherlock’s reaction and his lack of saying anything to her (granted she did just promise to talk to John, but work with me here) I had to look over the whole episode.
All the actions that make me wonder who is Mary Morstan:
- Mary is not immediately angry or upset at Sherlock. If the man I loved a great deal who had been suffering from the loss of his best friend all of a sudden is confronted by that friend who is “Not Dead” I would have been shocked but I wouldn’t have laughed it off like Mary did.
- When Sherlock mentions the fact that Mycroft knew, John was about to get angry and Mary said that Sherlock needed a confidant.
- Mary lied about liking the mustache.
- Mary is not mad at Sherlock for John, in fact she is understanding of Sherlock.
- She says to him, “You know nothing about Human Nature.” She probaby has a great idea about human nature herself. She is a nurse and nurses need to understand people since they deal with them.
- She teases John for shaving the mustache for Sherlock.
- She is taking all of this very well. Granted she wasn’t friends from the guy, but she heard all about it from John.
- Mary left John’s office to go somewhere? Where did she go to?
- The texts Mary receives from an “Anonymous” person. Why did Mary receive these texts? If this person was going through John to get through Sherlock why would he go through the trouble of texting Mary? Seriously if this person was somehow smart to get Mary’s number he could surely get Sherlock’s number.
- Mary said it was a skip code. Mary knows codes! There is more to Mary for sure.
- Also there is the matter of the person texting knowing Sherlock was reading the phone. How did the person who had just texted Mary know he was talking to the Sherlock Holmes? Why go through all that trouble and not just text the very person you are wanting to hurt?
All the other questions I have:
- What did Mary do before she met John?
- How did she meet John?
- What is the relevance of Gaurdian?
- What is Mary lying about?
- Why was she not upset at Sherlock?
- Why did they go after John?
- Why contact Mary and Not Sherlock?
- What happened between Mary getting the texts and meeting up with Sherlock?
- Where did Mary go after she left the office?
SPOILERS
***The guy at the end of the Episode is Charles Augustus Magnussen and we will being seeing more of him in the next episode, but we wont see all of his face until the last episode.
My Three Theories About Mary Morstan:
- Mary is being Blackmailed by Charles Augustus Magnussen. For what I don’t know, but she is an innocent victim of hims because she is being blackmailed. I have a feeling that maybe someone who is under her protection that she is a legal “Guardian” of is a risk. Also this would cover the term “Secret”
- Mary is a former agent of Magnussen and maybe she became the Guardian of someone. As a result her life is a risk and everyone around her is at risk as well. The person who texted her is Magnussen. For Mary to have been an agent of Magnussen she would have to be “clever” and she is very perceptive when it comes to human nature. A agent would have to be.
- Mary is still an agent for Charles Augustus Magnussen. Now if she planned on blackmailing John, but than developed feelings where she tries to break away that could be something. Either that or this is all going according to plan. I mean she did tell Sherlock it was a Skip Code.
What will happen to Mary?
- Her past will be revealed.
- It will shock John.
- Sherlock will be slightly shocked, but not much.
- Mary will die by the end of the Series 3.
Do I Sound Like Anderson yet?
My Renaissance 
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Hi, Great post 🙂 I think you’re right, but I hope that Mary lives – John has suffered enough already and it would over shadow series 4 for me. Plus I like Mary and John together and they both work well with Sherlock, their comic timing is excellent.
One point I would like to add, the focus on the word ‘Guardian’. Mary is an orphan (or so she says). Perhaps CAM is or was her Guardian, hence why she looked so uncomfortable during the telegram read outs?
Also, 2 years seems a bit short for someone like John to get over the death of Sherlock and marry someone. His previous relationships lasted about 2 minutes because Sherlock got in the way. Yet John understandably grieves for his best friend, returns to therapy and yet manages to successfully sustain a romantic relationship, all at the same time in the space of around 24 months … huh? Sorry but I’m not buying that.
I can understand why John would be attracted to Mary – she is after all a more human version of Sherlock. But what attracts Mary to John is less clear. She agrees during John’s attempted proposal that she is the best thing that has happened to John, but no mention that he is the best thing to happen to her. Odd when she is an orphan with few if any apparent family.
What do you think about the term ‘shortsighted’? Do you think that’s in relation to her eyesight or her thought processes? She is after all deemed as ‘romantic’, yet ‘disillusioned’. She is good with words (linguist, code breaking, excellent memory etc) yet went into nursing and not journalism – this despite CAM owning a newspaper empire??? Hmm
I’s better stop, before I start sounding too much like Anderson too!
I think John would have turned to someone during his grief. I would not be surprised if she helped him through it. Also he said during the proposal they hadn’t known each other long, so anything is possible.
Also if you look at John Watson’s blog it appears that it’s only been a year. Begin by looking at June16 Untitled check out the website http://www.johnwatsonblog.co.uk/
OK, maybe I can accept the quickness of it all from John’s perspective – but from Mary’s, for me it doesn’t quite work. It’s a little too near the ‘Florence Nightingale effect.’
I’ve read the Watson blog, but I’m not sure the timeline works. They are on honeymoon in August, yet the wedding was back in May. Hmm this is a case worthy of Sherlock Ho…. ahem!
Or Mary could have been CAM’s former lover (the word lover comes up separately as well as in the phrase “Cat Lover”) and is the Guardian of his secrets!
Just call me Anderson!
I didn’t think of her being CAM’s lover. I like that a lot
In “The Empty Hearse” the film of the carriages is called “CAM,” so perhaps Magnusson is behind Lord Moran and the spy ring. As a reader of The Guardian, maybe Mary is a disillusioned idealist/ secret agent or someone like Valerie Plame. John reads the Guardian, too, and they are both liberals. I would like to see her live, but she probably knows too much about powerful people. I certainly hope she is not one of Moriarty’s tools….