Is there some kind of inside joke among the writers that makes them always screw O'Brien over?
-He gets wrongly tried by the Cardassians, gets stripped, gets a tooth ripped out, and almost gets executed.
-As a clone, everyone treats him like crap, his daughter hates him, and he gets killed.
-He gets put in a "mind prison" for 20 years, kills someone in cold blood while there, and has to live with the PTSD afterwards.
I'm sure I'm missing some others as well. I just feel so bad for the guy...