I figured it out! The Red Angel is the One from Babylon 5—Jeffrey Sinclair. He's unstuck in time looking for Babylon 4 so he can steal it.
The Red Angels would have to be scientific in nature for Spock, who was haunted by them since childhood, to be such a science believer in TOS. If they were revealed to be divine, Spock would probably be joining Sybok's crusade. I'm thinking with the tachyon element in play that the Red Angels are the builders of the Guardian of Forever. That will be another tie-in to TOS that Discovery seems so hard to be building towards lately. Obviously Spock won't be aware of this as he doesn't know about the Guardian of Forever, but the audience (and maybe Burnham) will be. The Guardian of Forever also is closely tied to Spock's childhood per Yesteryear. And it's one of the few technologies that can send people not just in time, but across large distances, as is needed for those World War 3 survivors.
Airiam. She's been in the background this whole time, and now with 100,000 years of intel at her disposal, will quit Starfleet and travel to the stars to solve all the Galaxy's problems throughout history.
I didn't feel as if they were ever doing that. Pike's comments in New Eden made it clear to me that at least he thought of it as extremely advanced technology... and that was only episode 2.
It's going to be Pike post The Menagerie in the far future. The Talosians are long dead despite Pike's efforts, and he is rummaging through their tech trying to get off the planet/die. He inputs the data for Earth, but since he failed Astrophysics in the Academy, he messes up and goes to WW3 Earth in front of a Church. He panics and accidentally transports them all to Terralysium. He realizes he was the Red Angel all along and proceeds to cause the rest of the 'Red Bursts'. Spock and Burnham will eventually speak with Old Pike who agrees to keep it a secret from young current Pike. They convince Starfleet to issue a ban to the Star Group Talos under the penalty of death. KIRK: What every ship Captain knows. General Order 7, no vessel under any condition, emergency or otherwise, is to visit Talos Four. MENDEZ: And to do so is the only death penalty left on our books. Only Fleet Command knows why. Not even this file explains that. (unlocks the magnetic strip) But it does name the only Earth ship that ever visited the planet. KIRK: The Enterprise, commanded by Captain Christopher Pike. Old Pike is the one who gives the idea to Spock about helping Pike in The Menagerie. Spock was bound by time paradox to do it which is why he acted so out of character helping Pike under penalty of death. Before Old Pike loses access to the technology, he decides to revisit 2257 Terralysium to meet with Jacob for one last time and retire. Pike: "I hope we meet again, Jacob." Jacob: "I know we will." This will put a cap on Pike's storyline.
It's either going to be Philippa or Michael. Absolutely certain. There's also a remote chance it's L'Rell on some kind of redemption quest.
OK, here's my half-baked idea. It won't happen, and I don't think I'd want to it, but... So we were told that this season would explain why Spock never mentioned Burnham, but narrative rules suggest that two people who begin in a state of estrangement will reconcile by the end of the story, so something's gotta give. Either Burnham gets erased from Spock's mind, or something happens to permanently separate them. Are there other options? So let's try this: the Discovery crew finds out that not only is someone trying to wipe out life in the galaxy, but that they're from the far future, 1000+ years, and they're trying to change the course of history to prevent the Federation from becoming what it will be. And the Red Angel seems to be trying to stop this. So Discovery will need to hop across 1,000+ years to solve the mystery and thwart the enemy. They're literally in a fight for the future. How will they get there? They can't use the spore drive--we saw how temporally unreliable that was--but they come up with a way to move just a skeleton crew (Mudd's time crystal?). How will they move the ship? There are two paths to the future: they're taking the short road, but the ship will need to take the long way round. So they give Discovery some simple automated maintenance and defensive subroutines and hop through time. They rendezvous with the ship to discover that she's sapient now, and calls herself Zora. And they realize that the thing that called them to the future was in fact Discovery herself, who has been sitting, monitoring, charting history, becoming alive. Some kind of downfallen Preserver-equivalent enemy has set out not to save but to end civilization, and they're reaching across history to do it by changing little things a la A Sound of Thunder. And it's bad news: the future, as it stands, is a place where things fall apart for the Federation, now the backwards-looking, self-obsessed V'Draysh. But Zora knows what needs to happen: send one of them back, using advanced future tech, to intervene in a few critical events, the proverbial butterfly effect. And someone, maybe Burnham, is sent through time at Zora's behest, fixing the timeline and thwarting the enemy in the guise of the Red Angel. In some kind of suitably epic showdown, everything the anti-Preservers have been up to is prevented, and a future where the Federation survives is maintained. But for whatever reason they can't all make it home, and Burnham and most of our cast (save Pike and Spock) are stranded 1000+ years in the future, with a sentient ship and a brave new world. But there's one last butterfly effect act that needs to be carried out to pave the way for the world that will be. The season ends with Christopher Pike returning to New Eden to welcome Jacob and his people into the Federation. OK, time to go to bed. (I don't really think this will happen. And I'd rather Disco stay in its century. But I'd love for Calypso to be relevant to what happens!)
I was wrong, he said, "so, it's someone." Weird how when the Red Angel appeared unexpectedly, it seemed do take 5 or so small skipping jumps to get close to the stronghold ship before emitting the EMP. Almost like a personalized DASH-suit was in play.
It's Tilly after bonding with May. "Everything you do is out of love" sounds like an angel (and she's already got the red hair!)
The Red Angel is a time-traveling Nirvana album cover. It's message which has yet to be decoded and translated is: "Come as you are."