This is my theory as to what the h is in Eren’s basement based on evidence found in actual series.
First off, take a look at the key.
looks normal, BUT WAIT WHATS THAT!?
It’s a TRIANGLE. The three round things on the key connect to make a TRIANGLE.
Now hold on to your Jean Kirschtein’s cause this is where shit gets real.
Notice anything about this picture of Eren???? No? Here, Let me help you.
Eren has an EYE.
So the clues are a TRIANGLE and an EYE. That can only mean one thing…
The Illuminati’s main base is in the basement. Need more proof?
The Illuminati movement was founded on May 1, 1776 in Ingolstadt, Upper Bavaria as the Order of the Illuminati. Hmmmm, Where is Ingolstadt? Germany. Eren’s last name is German. PRETTY FISHY.
"Butt y is the Illuminatis the big seacrut???" Well picture this…
The illuminati have just made a thing that turns humans into giant humanoid beings that can regenerate when hurt. They plan on using it for world domination, but it backfires and the human race is driven to the brink of extinction. Eren is the descendant of one of the last surviving Illuminati members. The basement is full of information about the Illuminati creation of Titans.