So I just started the new Thieves Guild questline like everyone else,
and a theory has been growing in my mind based on both the first quests and the preview images/articles ZOS released before.

My theory is that Lord Basil is actually Sheogorath.
I could be completely wrong, but there have been little hints that I wanted to share them and see what everyone else thinks

Things that stood out to me:

• 1. He resembles Sheogorath..
  not just the face... but also the clothing, posture, it immediately reminded me of Sheogorath!
  
  
  
  
  
• 2. His introduction was strangely minimal...
  in the "Meet the Characters article" Lord Basil is barely mentioned and doesn't even appear in the promotional image!
  Maybe that's intentional...
  
  
  
• 3. Sheogorath is known for disguises and taking different forms..
  We've seen him appear as completely different people (or even creatures) before... or possessing someone, but it wouldn't be out of character if the "real" Lord Basil isn't actually the one we're speaking to...
  
  
  
  
• 4. The butterflies...
  the butterflies associated with Sheogorath appear in the promotional artwork. that can't be just a coincidence..
  
  
  
• 5. This one is definitely more speculative.. but why Lord Basil?
  Basil immediately makes me think of the color green. Sheogorath isn't usually associated with green... unless we're talking about the Dementia side of the Shivering Isles, which is swampy and green
  
  

My theory about the story:
I think Lord Basil is really Sheogorath, and he's manipulating Quen into retrieving something from the vault.. not for wealth, but for some powerful magical artifact!

Things I noticed after only completing the first quest:

1. Lord Basil is the one who originally approaches Quen with the plan

2. When speaking with him later, he says he's "only here as a spectator."
that line immediately stood out to me.. daedric princes often prefer nudging mortals into doing things rather than acting directly

3. The codex.
When the codex is recovered, Quen suggests that Lord Basil might be able to help decipher it.
That immediately reminded me of the original Mages Guild storyline, where mysterious tomes had to be deciphered.
Lord Basil also mentions that the vault contains not only riches, but magical knowledge and power.
(That feels like exactly the sort of thing Sheogorath would be interested in)

A possible connection with his daughter, Selene:
this is probably the weakest part of my theory, but I thought it was worth mentioning

1. The name "Selene"
we've already had a notable character with that name in ESO. Selene from Selene's Web and the Lair of Maarselok

2. She's described as a priestess of the forgotten "Shagrath"
We know almost nothing about this Shagrath.. it remains a mystery...
but I couldn't help noticing how similar the name sounds to "Sheogorath"

3. Selene is associated with changing forms, which is another recurring theme connected to Sheogorath

4. She's described as a remnant of an original "chaos"... Again, chaos\madness is one of the defining themes of Sheogorath

5.Once again there's a strong association with green and wilderness

Obviously, this could all just be me connecting dots that aren't actually connected... some of these points are definitely stronger than others.
Still, I can't shake the feeling that Lord Basil is more than he appears, I guess I will see soon
What do you all think? Am I reading too much into it, or has anyone else been getting Sheogorath vibes?