It came out of nowhere.
Felix was flying through the shattered skies, enjoying the sights of the many portals, taking the occasional selfie. Then the threads of energy formed between the portals. Felix almost flew straight into one. That kind of thing never happened. And the threads multiplied and filled the air until one...
...Felix now is somewhere else entirely no idea how he got here. While flying through the wilderness the pain starts and eventually culminates with a blood-covered pebble coming out of his mouth. Which was only supposed to happen if Felix was somewhere else so far that the magic that allows his immortality couldn't reach and the only possible place like this would be another universe entirely.
An hour, he gives himself that much time and uses it, but by then Felix decides that crying isn't useful anymore no matter how much he wants to.
Instead Felix searches for civilization, since he is going to stay in this world for the foreseeable future.
Okay, Felix will follow Gren-room-wards and search for a gray quartz crystal somewhere in her bed or something.
Her room is filled with all sorts of strange mementos. A few other crystals, woodcarvings of fantastical creatures, a brass statuette that softly glows, a flower that turns towards the nearest person and hums softly.
Regarding the crystal, "Is that the thing?"
"Yes. How it go here?" Felix says, "Urgh, I need to find a place to sleep and create a couple of portals. I... it might be a good idea if I go alone, if she has a dimension it could have anything."
"Weird stuff tends to happen around Copycat. Not too often, but- If something weird has happened, decent bet she's involved. If you say it's dangerous, then yes, go alone."
"I need a place to sleep, and to know what Copycat looks like to identify her in the pocket dimension."
"Guest bed. Hm, we don't have portraits, but..." She gives a servicable description, from height to hairstyle to skin tone to her grey-green eyes.
Felix nods in agreement and lets himself to be conduct to a place to sleep in.
Yup, that is a pocket dimension.
He basically only stays asleep just long enough to create two portals and a quick check to see if he can make his own world technology (he can). One between Earth and his own dimension and another between his own dimension and Gren's.
Then he wakes up. Is there anyone around he can report this to?
The Witches have gone off to do other things, but McAllister left her assistant with instructions to 'tell me what he says when he wakes up'.
Felix explains that Gren indeed has become a Dreamshaper (his kind of magic dimension conjurer) and Felix is going to rescue her. He explains how portals work (requires you to do specific actions, this are the specific actions for the ones he made). If something happens, Felix can try destroy this body and it will take a week before he gets a new one up and running and they will need to rescue Gren themselves or keep her alive until Felix can try again.
Also, Felix checked and he can do conjure his amazing future technology and that is extremely good news even if this isn't the time for celebration.
If all that is understood, Felix will go over Gren's dimension.
They're unhappy about not knowing what's going on and demand fairly extensive explanation of dreamshaping. But they get the urgency. They will have little idea how to rescue Gren and will default to brute force once through the portal - unless this is unwise somehow?
(The technology is, indeed, good news. Perhaps they could get a quick sample of textbooks to throw at some engineers, if it will only take a moment?)
The pocket dimension can contain anything so maybe it will be filled with innocent children or monsters that look like innocent children. The way to solver the trouble is finding the Gren-projection that is in there and bring her through the portal. Felix can't stay dead so it makes sense for him to go instead of risking mortal lives.
Felix retrieves some books he created as a text, it is pretty random engineering, but it looks legit and rather advanced.
Boreal forest, night sky. Rock formations here and there. Standard forest sounds and scents... But with a sort of metallic layer over them.
It would be pretty if he didn't fear of being assaulted by a monster or something.
He takes flight. Any sign of Gren?
The forest turns less boreal and more temperate towards a rocky hill in the center, where a building with huge glass windows shines with too much light.
...Did he see something out of the corner of his eye? A red glint from the forest?
Did he? Well... does it help if he sends some fire balls to illuminate in that direction?
If by 'help' you mean 'elicit a barrage of red beams', then yes!
Also, a near-silent metallic... Cyborg owl? Tries to dive-bomb him, scratching with claws and beak. This one doesn't seem capable of lasers.
The metal owl gets a shallow scratch in, but melts readily. Whatever was below seems to have decided to hide in the thicker trees for now.
Ok, Felix will start gathering electricity so he can be ready to strike. This is his life now, apparently, throwing thunderbolts at giant monsters.
The monsters do not attack again. He's being watched as he approaches the shining house(?), though.