Originally Posted by Nyloth
...right now companions do not react to our race in any way...
I have noticed a scant few instances where they do refer to your species:
  • Lae'zel mentions it when she insults your nose after you free her (after you mention her species).
  • When Shadowheart comments that she never thought she would have cared about tieflings, she includes you in that if you are a tiefling.
  • Astarion says he's "not normally impressed by people of your stature but..." if you're a halfling (and presumably if you were dwarf).