Complex sentence: One of the reasons for this is that house slaves acted as the slave master's spy on occasion, they would report to the slave master on runaway plans and even who was slacking in the field when they should be working.
Split into simpler sentences: One of the reasons for this is that house slaves acted as the slave master's spy on occasions. They would report to the slave master on runaway plans and even who was slacking in the field when they should be working.