Eurus: I have a master plan to finally break Sherlock!
Moriarty: Ah, wonderful! What's my part of the plan?
Eurus: Well first you, of your own accord, have to come up with a series of impossible mysteries for Sherlock to solve.
Moriarty: Okay...sounds like I'm doing a lot of the work...
Eurus: And then you have to let Sherlock outsmart you, and pretend to be so upset that you kill yourself.
Moriarty: So I *pretend* to kill myself?
Eurus: No, actually kill yourself.
Moriarty: So just...okay...once again, sounds like I'm doing *a lot* of the--
Eurus: Now, before you die, I need you to record some close-ups of yourself saying the following phrases...
*She hands Moriarty a script which he leafs through*
Moriarty: Most of this is train noises! Are you going to be doing ANY of the work?
Eurus: Oh of course! I'm going to dress up as Zoe Dechanel on a bus and seduce Watson.
Moriarty: Oh, that's clever! Wait, why?
Eurus: For...uh...to be a sort of mysterious and foreboding presence in Sherlock's life.
Moriarty: Right, in *Sherlock's* life. So why torture Watson?
Eurus: So I can shoot him.
Moriarty: Ah! Brilliant! Killing Watson will--
Eurus: No, no. Just with a tranquilizer gun.
Moriarty: But...why?
Eurus: To announce that I'm Sherlock's sister! And then he'll tell Sherlock!
Moriarty: So you're going to tell him you're Sherlock's sister and then shoot Watson...on the bus?
Eurus: Oh! No. I'm also going to pretend to be Watson's therapist, who will *not* be Zoe Dechanel.
Moriarty: So you can pointlessly shoot Watson with a tranq?
Eurus: Precisely! AND, to *really* be a nuisance, or something, I'm also going to pretend to be a girl that Sherlock will be investigating on an unrelated case that I'll have no idea he'll be investigating in 5 years because it would be literally impossible for me to anticipate that. But rest assured I'll dress up as *someone* related to *some* case, and that someone will leave Sherlock a note with "Miss me?" written in invisible ink!
Moriarty: Miss me...that's on the script you handed me.
Eurus: Exactly! I'm going to play a video of you saying "Miss me?" to Sherlock so he thinks you're still alive!
Moriarty: But I won't be...Ohhhh! So we're going to set up an elaborate mystery *before* I die so that it will appear to Sherlock that I've set it up *after* my death! He'll think I'm still alive, and it'll drive him craz--
Eurus: Right, right, but no. No, there won't be an elaborate mystery under your guise. Just little notes that say "Miss me?" Because in actuality it'll be *me* he's missed! Not you! Then once I've revealed myself as his sister, I'll make him go through a gauntlet of deduction! And *thennn* use those fun train sounds which you're going to record for dramatic effect!
Moriarty: But then...excuse me, madam, why do you need me for your plot at all?
Eurus: To confuse the audience!