In The Kite Runner, what is Hassan's reason for deciding to move back in to the hut behind Baba's house instead of into Baba's house with Rahim Kahn?

Given that Hassan is a very, very intelligent man and one
with a relatively wide experience at the time he returns to Kabul to live with Rahim
Kahn, it makes sense for a number of reasons that he live in the small house rather than
the large one.

He understands his place in the society of
Afghanistan and knows that it won't be seen as proper for him to be living in his former
master's house regardless of whether or not he has permission.  He is comfortable and
proud of the role that he plays in supporting his former master and his former master's
friend and the household and he doesn't need the comforts of the big nice home to add to
that.

He also likely feels comfortable there, having grown
up there.  The bigger house may have presented an uncomfortable circumstance for him,
one he'd rather avoid.