The Targaryens left behind many of the darker customs of their homeland.  They stopped the practice of slave ownership at some point in their history on Dragonstone.  Aegon fought against the slave-owning state of Volantis and burned their fleet.  Many readers believe the making of Valyrian Steel involve the sacrifice of humans.  Even knowing the value of the metal, the Targaryens themselves did not make attempts to manufacture the weapons for themselves. Prominent Targaryens like Rhaegar settle