In terms of Eichen House I thought and still kinda think that the reason he locked himself up there was because Claudia asked to be locked up there after some kind of incident, possibly one where she hurt Stiles or someone else. A case of ‘history repeating’.
I think definitely the door ‘no one’ can open goes into the supernatural isolation level and now that you mention it, yes. Notice that the second Stiles finds that door he forgets all about trying to get out of Eichen House and his single goal becomes to get into the ‘basement’.
When he does get into a basement with Malia he finds a lot of papers of trepanation and Rhys’ body but not what was behind that door.
And what’s behind that door? Dr. Valeck, that’s what. I’m suddenly unsure if Stiles was sensing something out or Dr. Valeck was calling him in.
A Promise to the Dead:
We find these eyes elsewhere, like Sean’s bathroom in “Muted”, I think? I haven’t gone back and rooted them out.
Morrell! She’s as missing as Danny this season and I’ve missed her but I’m not sure whether or not — like Danny — she’s really ‘missing’ so much as some kind of scheduling conflicts with the actor. (We’ve seen #6, Danny, on the field and at the party in “Perishable”, Danny is there but not Keahu. QQ.)
I think this is related:
We’ve got the ongoing story of Dr. Fenrir. He used to work at Beacon Hills’ Memorial and checked out Jackson’s neck in “Wolf’s Bane” and diagnosed him with aconite poisoning. Between S1 and S2 in the "Search For A Cure" mini-series he was confronted by Scott and Stiles, they acquired his knowledge of werewolves and, specifically, the Hales, and Scott showed him werewolves were a real thing.
Move forward to this season. Suddenly he’s working at Eichen House (understandable once he was initiated into the certainty werewolves are real), where Morrell also works at least part time. Pretty sure he’s also the voice on the tape left in Kate’s car, which may be from one of his many online lectures back when he was trying to convince the world at large of the supernatural (“Search For A Cure”).
I bring this up because I think, yes, Dr. Fenrir and Morrell are in this case potentially interchangeable in terms of who fills the role in the Eichen House scenes based on availability. I don’t love to make guesses based on stuff I can’t evidence within the show, but based on the characters’ histories that’s the sense I get?
So, yes, I think Morrell works there primarily because of the ‘secret’ floor.