These are the parts we seemed to have solved (to reasonable conclusion) before getting the newest Tachyon voicemail (with the song "My Sister" on it.
This was based on reading all of these threads and trying to make sense of the most likely answers and what had been confirmed (that can be):
The Culper Ring is who Tachyon works for.
Cool reveal. Assuming of course that was the connection between NILI and SETAUKET in those file names. From reading up on both it suggests the tie between those two words. It also fits some facts we've received leading up to this point: Tachyon is part of a mysterious law enforcement/spy agency with ties to US GOVT and code names/code numbers (10033)
Tachyon is pissed off at OpAphid, and may have taken out a Watcher
The note about "sorry about the mess" suggests Tachyon at least bloodied her "sitter" (and OpAphid confirmed this). Her "take no prisoners" attitude seemed suggested by saying she couldn't follow the book "The Art of Peace," and also by the playing card with the X on it. It seems like Tachyon was giving it back to someone, which makes me think it was 10033 (Brother) who gave it to her. The Queen of Hearts brings OpAphid herself to mind (Red Queen, Alice in Wonderland), and the X would mean that Tachyon has targeted her or marked her for death in some way (obviously OpAphid is still alive though). So it's kind of a threat.
Tachyon left a guy behind, or made a choice over a guy or something greater.
The random note about choices and thoughts about "him" suggests maybe Tachyon met a boy while undercover in The Order? So her choice was to leave? Or maybe she was seeing someone before going undercover. Nothing else from the drop seems to explain this, so it might be referenced again in the future. It's not Brother though, because it is asking someone to pass word along...in-game, from what we know, Brother or people on behalf of Brother are who the drops are meant for. Speaking of which, we haven't heard from that simpleton in awhile...Perhaps he found some distractions online after getting clarity on the "any key" issue.
The I in APHID = INFILTRATE.
The I in APHID is infiltrate and Tachyon turned the tables on OpAphid by infiltrating them.
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HOWEVER, we seem to be missing a few things
It really does seem like we missed something important because a few things stand out that seem semi-related to each other but unsolved to a conclusion.
Here are the loose ends that I think tie into the "My Sister" revelation:
Why did Tachyon infiltrate The Order?
Her anagram said she "sought" to infiltrate. So she had a motivation going in. And her above note to the mysterious boy talked about choices. So it wasn't like she was forced into the assignment.
What was the relevance of Gemma's video "They Disappeared" on the memory card?
It's file name was HMM and...see below.
Why was Tachyon's password SASCHA?
Gemma says it was the name of the dog that the family of the girl had in "They Disappeared." The other times a password or key were a word, they had relevance (like GPS or TACHYON from her first drop).
Who was the birthday card was meant for?
We know it was meant for a female. Some people are guessing Bree, but it doesn't fit with the other loose threads from this drop. And while Tachyon is concerned about Bree, it seems odd Tachyon wouldn't be addressing videos directly to Bree if she already knew her. She has asked others to tell Bree things. So it seems odd Tachyon would write such a personal note to Bree given their (lack of a) relationship. Also, this drop seems VERY heavy on Tachyon's backstory (while OpAphid focused on Bree and Daniel with Saturday's "Adventures in Babysitting" video).
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IDEAS of what we overlooked?
We got the phone number from the book. It was the hardest part to figure out. It revealed the song "My Sister" by Juliana Hatfield.
Given the unanswered questions from before, this seems to answer them.
Or am I totally baked?
)