Superficially, Harmony do not appear to be a Shockpack. But it does not take long interacting with them to start to understand the depth of their psychosis. Members of Harmony come together out of their hatred for the ugly state of the world, and a desire to only surround themselves with things of beauty.
All members of Harmony are extremely graceful and attractive, more often than note involving cosmetic surgery or implants. They don't care about what's on the inside, only on the outside, so beneath the surface are often weapons and combat implants to boost their speed and agility so they are capable of beautiful acts of slaughter.
Harmony members are often equipped with augmented reality implants, allowing them to edit their perception of reality. In place of the ugly sights sounds and smells of the slums, they see a fantasy world in order to avoid dealing with reality. When the reality seeps through, when the filters are not tuned right to keep out the world, they turn cruel and violent as they seek to exterminate the things that upset them. Some even turn the violence and cruelty they inflict into shining pristine acts of delight, but some do not need that filter as their hatred for ugliness turns into a love for causing suffering to ugly things.
Because of their superficial beauty, Harmony attracts members who highly value beauty but have little else that they value in life. Members are brought in by the fantasy of no longer dealing with the ugliness of the world, and only seeing beautiful things. With nothing else of value to live for, even those without a history of violence will either embrace the cruel ways of Harmony or be destroyed by the Shockpack.