Guesses involving the Big Bad or Possible lack there of.
Aizen is the one behing Rainbow Dash's Mind Screw
Kyōka Suigetsu is behind everything
- Further speculation also believe it is in a bankai state which would let it screw with the ponies memories, and is also female.
There is no big bad
- The whole thing could be some kind of contamination as drugs were found in RD's system
- something got into the water, then into some of the plants, which were then harvested and spread around, Which the animals could tell and thats why they were freaking out at fluttershy's and Ulquiorra couldn't see anything with his pesquisa.
- Which would also explain what Chrysalis said as she died. she was only hearing a voice.
- This could also be another layer of the Big Bad's deception trying to make it look like this.
Discord is behind everything
- He brought Ulquiorra because he wanted a challenging opponent.
- Alternatively this could be a ploy making him to look like the Big Bad
Another country's government is behind Rainbow Dash's Mind Screw
- Drugs were found in Rainbow Dash's system meaning it could be a deliberate attack to take out Equestria's highest, to a country that doesn't know about Ulquiorra, defense.
- This is Chemical warfare from a different country and this is prelude to a war.
- Ones with possible motive would be the Gryphons wanting fertile land and not wanting to be dependent on imports of meat.
The real Big Bad of the story is the Everfree Forest itself. It's releasing neurotoxins into the atmosphere that are driving the ponies insane.
The big bad won't be met by Ulquiorra until chapter 108
Ulquiorra will be the new element of loyalty, at least until the big bad is beaten
- Celestia, "Loyalty? Was she... yes she was seeing some measure of loyalty and respect. A great deal of loyalty actually... at least for one particular individual." Foreshadowing?
- May have been jossed as of Chapter 59, but still possible.
Discord needed Ulquiorra because he couldn't get involved himself
- Think about it. We saw in Twilight's Kingdom that his magic could be stolen. This means his powers aren't infinite, and he can only do so much on his own.
The absolute control spell mentioned in chapter 60 will be used to get rainbow reconnected to the element of loyalty
Ulquiorra will go with Twilight to the "Equestria Girls" universe.
- He will back to being invisible to those with weak reiatsu and the only ones who can see him will be The Mane Six, and Sunset Shimmer.
- He will also be able to use his descorra to go between the two realms.
The two orderlies from chapter 67, Charley and Corners, and going to be working for Celestia in the coming chapter.
- Confirmed in Chapter 67 supplemental at least for Corners.
Ulquiorra will be some sort of Arch-Enemy for Cadance
- Cadance the princess of love, who prefers informality and uses magic to "remind" ponies that they are in love dealing with the stictly formal, nihilistic, war veteran.
- Ulquiorra will also question how she is the ruler of an intangible concept, point out her magic is basically mind control, and draw comparisons that both Chrysalis and Cadance use love based magic that alters the mental state.
Cadance will take pity on Ulquiorra for not being able to comprehend what love is.
Ulquiorra will become known as different names by different nations.
- Not many know his name for those that do it is usually difficult to pronounce, and word of his feats are spreading despite Celestia wanting to keep them down.
- Possible ones include
- The Black Death of Equestria slight irony with him being mostly white, or involing him blotting out the sun at one point.
- Equestria's White Death: Him being a killing machine and completely in white
- The Equestrian Phantom: His referring to himself as a ghost so he doesn't have to explain what a hollow is several times, and his ghostly appearance giving it spread.
- The God of Death: Purely for irony to the translation of Shinigami.
One or more of the mane 6 will hollowfy
- Ulquiorra will have to fight the one that does in order to keep them from completely hollowfying.
- Possibly Jossed as of chapter 78.
The S.U.Ds are results of unicorns trying to infuse dark magic into their core
- The unicorns try infusing dark magic to gain more power, then when there is too much inside they explode.