A Pome a Day for a Year

I wonder about Sen a lot,
ever since I traversed his fortress
in the murky world of Lordran.

Who is Sen?
Why did he have a fortress?
What was the deal with it?
Did he live there?  

I have to assume that no,
for I saw no bedroom or toilet

(And I know there are a lotta weirdos
in the universe of Dark Souls,
like a serpent with a silky voice who eats you
to carry you to a firey cup,
or the guy who loves staring directly at the Sun,
but has 20/20 vision), 
and these would be required to turn a building of traps
into a domicile of eccentricities.

Sens Fortress, no doubt, has lore revealed via items
and discussions with hollows (some have huge hats).  
However I play those games for the vibes,
and am as clueless as my character,
who wanders these places flailing with attacks
and getting cornered to death.

Sen, though.  Sen?  Close to Sun
Uses a load of balls as traps and blocks
and the Sun is technically a big ball, 
though you would not get that rolling through a corridor!
A) it would melt 
and B) it would play merry havoc with the gravitation pull on Earth.