"fifth dimensional".
Dual existence in 4th dimension and physically in 3rd - just like Bran - otherwise you can't explain how Samwell and Jon killed the misty frost ice embodiment's - unless Jon was unknowingly in a 4th dimension himself - But Samwell saw them and killed one also - unless Samwell is secretly someone else (this is possible in some theories) - but because other NW's seen them at Hardhome you know everyone can see them.
There are caves in the Frostfang Mountains - and for a while I thought the Others were in those caves projecting themselves like Bran does - but now that Bran can move about that theory is kaput
So now you have to wonder about limitations of movement - because everything ASOIAF is a factor of 3 - I suspect that when Bran was 'marked' they will now pursue him and follow him - but the magic of the Wall will keep both them and Bran North of the Wall - as he can not go South of the Wall himself as he is not a member of the Night's Watch, so besides just not knowing the oath to pass through the Black Gate he is stuck North of the Wall. If the Wall comes down all pass. Or if someone lets him through the black gate like BenjenWightColdhands he may pass - but I'd suspect BenjenWightColdhands is eventually killed before they reach the Wall/BlackGate - most likely just as they get there. So it matters greatly if Doloros Ed sees Bran, comes out of Castle Black gate, tries to save an approaching Bran (maybe Meera dies) and then the last Night's Watch dies - bringing down the Wall. Maybe a howling wolf is the horn from afar - Ghost.
Cave Bran - Limitations of Movement-Dreams
| -- | Others | Bran |
|---|---|---|
| PHYS1 | Frostfang Caves | BR's Cave |
| Dream | NWall | Any |
.,.
Mobile North Wall Bran
| -- | Others | Bran |
|---|---|---|
| PHYS2 | NWall | NWall |
| Dream | NWall | Any |
.. After Wall Comes Down - No Magic Barrier
| -- | Others | Bran |
|---|---|---|
| PHYS3 | Any | Any |
| Dream | Any | Any |