A question on Dragons and the Lifestream

I recently did the guildhest with Buso and read that the heist NPC mentioned our lifestream would not take the aether of the hippogrpyhs, leaving the blue flames. This made me consider the dragons. Despite knowing that Midgardsormr's origins are vague, it's at least hinted he came from a different setting to our own. This in turn made me wonder... does our lifestream accept a Dragon's aether? Dragons are not native to our Hydaelyn, but if they came from another planet/star/ what have you, does the lifestream then function as a system of the entire universe, not just our planet of Hydaelyn?

I apologize if I missed some information somewhere, this has just been a question on my mind for a good minute.

My theory is that Midgardsormr is the alien, but his covenant with Hydaelyn allowed him to nurture his eggs with Her aether and thus grant them, and their progeny, their place in Her Lifestream. It also explains why he can die and just hang around his corpse for fifteen years before deciding to reboot.

Since we are talking about dragons, anyone else notice that we have dragons popping up in void related areas quite a bit? We have a rift Dragon in Lost City HM, a Zombie Dragon in LotA and now more dragons in Dun Scath. Could Midgarsormr be another refugee from the 13th world?