The fiend totem rage powers are OK, but seem to be based mainly on the infernal (cornugon, hamatula). To help introduce a bit more variety, I came up with the following rage powers based on the slimy demodand (as the type that is "frequently put in charge of gathering and keeping slaves," they would also likely be the type most likely to spawn fiend-blooded/half-fiend offspring):
Demodand Totem (Su): While raging, the barbarian's skin drips acidic slime. Natural attacks (such as the claws gained from the lesser demodand totem rage power) deal an extra 1d6 points of acid damage. In addition, opponents that successfully strike the barbarian with an unarmed strike or natural attack take 1d6 points of acid damage. A barbarian must be at least 6th level and have the lesser demodand totem rage power to select this rage power.
Demodand Totem, Greater (Su): While raging, the barbarian exudes a nauseating stench. Each living creature within 10 ft must make a Fort save, with a DC of 10 + 1/2 barbarian level + Con modifier, or be sickened for as long as they remain in the radius and until the start of their next turn on leaving the radius. Creatures that succeed on the save cannot be affected by the stench for the remainder of the rage. Creatures with the stench ability or immunity to poison are not affected. A barbarian must be at least 10th level and have the demodand totem rage power to select this rage power.
Demodand Totem, Lesser (Su): While raging, the barbarian gains two claw attacks that do 1d6 points of slashing damage (1d4 if small). These are primary attacks.