Complex sentence: Over time, the character has become increasingly cruel, callous, selfish, self-centered, self-interested, devious, crafty and depraved, although the Smith family are curiously oblivious to his nature.
Split into simpler sentences: Over time, the character has become increasingly cruel, callous, selfish, self-centered, self-interested, devious, crafty and depraved. Although the Smith family are curiously oblivious to his nature.