Amelia is the one who is talking in the intros, not Jake.So far we haven't seen Jake talk a single time, and have no real evidence that he is even capable or would feel the need to give these monologues. In the Season 1 finale, we hear Amelia talk, and her voice sounds an awful lot like the opening narration. Considering that they're both young children, it can't really be told whether or not the voice is male or female.
Jake isn't muteHis opening and closing monologues clearly demonstrate a high level of intelligence and he speaks in them. I posit that he actually is capable of speaking, but doesn't do so because he hasn't come up with any way to verbally communicate what he sees. (Or perhaps is simply aware that if he were to tell people "I can predict the future", they would think he was insane. Given his obssession with the numbers and patterns, it's likely that he doesn't consider anything else worth communicating about, so he simply doesn't talk.
The Japanese girls will eventually become part of a much larger Story Arc.They've appeared in three consecutive episodes so far. No way is that a coincidence.
Teller is crazyIn school, Teller was really into math and sci-fi. Rather than become a writer or a mathematician, he slowly descended into obsessive madness. The series is his hallucination.
The numbers are the will of a superhuman entityAmelia was its first victim, and now Teller's bit the bucket too. Its influence on a mortal manifests itself as brain damage - hence why Teller's enlightenment was treated as an aneurysm, and Jake has an Ambiguous Disorder in-universe.
We've already seen a good number of the "36" other than JakeThe few characters shown who can see numbers like Jake are: Jake himself, the Invisible Prince, and Amelia (also possibly Teller but he's dead), so we can probably assume all of them are "36." Avram also states that the "36 righteous ones" are those who make small changes to alleviate the suffering of the universe. But oddly enough, his explanation in Music of the Spheres doesn't talk about Jake's mutism or numbers, so people who are "36" might not necessarily need to have mutism or see numbers the way Jake does, but simply be characters who do good to everyone around them. The "36" may also include certain recurring characters who have done good to others around them:
Touch is Pi: The Series
The "36" start talking when they turn 13.As long as we know, Jake's the youngest of the "36" and he has being alive for 12 years. Amelia is 14 but the videos (I think) are from a year ago. Also older "36" talk normally and had joined into society quite well. In season 2's premiere, Jake declares that his mutism is about to end soon, so my guess is he'll start talking as soon as his 13 years of life come.
The death at the end of "Reunions" was faked.There's most likely a reason why it was staged as an offscreen Disney Death. It's not unreasonable to suggest that Lucy is being held in a secret AsterCorps facility somewhere (which may or may not be the Teller Institute.)
The Mental World Amelia and Jake can access is a representation of the Garden of Eden.So far, only the 36 (well two of them) righteous ones can access it. By there nature of being righteous, the 36 are possibly pure enough that they would not be barred from it.
Aster Corp wants to use the power of the 36 to rule the world
The reason the events of Revolution occurred was that at least one of the 36 got killed off.According to the concept of Tzadikim Nistarim, there are 36 righteous souls who keep the world from being destroyed by God just by existing. So when one of them got killed off, God came up with a particularly cruel punishment for the Earth by shutting down the power worldwide. Now that group of individuals is struggling to stay alive, as well as get the number back up to 36 in the hopes that God will reverse the punishment.