6dc5455c____The_Coppermind___17th_Shard__Entry
[Chapter] 75 [Entry] 
Each Hemalurgic spike driven through a person's body gave Ruin some small ability to influence them. This was mitigated, however, by the mental fortitude of the one being controlled. In most cases—depending on the size of the spike and the length of time it had been worn—a single spike gave Ruin only minimal powers over a person. He could appear to them, and could warp their thoughts slightly, making them overlook certain oddities—for instance, their compulsion for keeping and wearing a simple earring.
The Hero of Ages/Epigraphs - The Coppermind - 17th Shard
Entry