Spoilers for Season 2 Chapter 1!!!
Who was Aerin? Many who didn't take that much opportunity to re-explore the Labyrinthine Cliffs upon the zephyrite's return might have missed this now notable NPC entirely. He seems to pop up entirely out of the blue from the opening to Season 2.
He actually was quite busy this last living story patch, but let's flash back to the first time the zephyrites showed up. Aerin was down at Bazaar Docks as an NPC you could speak with. All he had to say was, "These Zephyrite people are truly amazing to have created such a mysterious airship home." That's all Arenanet wrote for him at the time. At their second arrival, Aerin was absolutely -GIDDY- to get aboard and become a fellow zephyrite. Once getting permission to become a member, he proceeds to run absolutely amok on board just losing his damn mind over how absolutely amazing everything is! So I decided to take screenshots, simply because I thought this chucklehead was adorably hilarious and wanted to save it for posterity. O_O Little would I have guessed what would happen next and he'd actually become an important plot point. What I find interesting that the hints in Season 2 implies that Aerin was Soundless, yet this doesn't really seem to be the case when he's gibbering with himself on board the ship. He's actively begging for the Pale Tree's help during one dialogue, he even says his journal is for those who do not have access to the Dream. Was he driven mad in the middle of the ride to Maguuma or was he already possessed with terrible plans? Did he try to become Soundless during the trip? You be the judge.