Everyone has regrets, but it takes a special kind of remorse to become a penitent, a herald so overcome with remorse that they devote themselves to an unending quest to redeem themselves and others. Many penitents were formerly heralds of a different sort who violated their oaths, but this is far from a requirement. Their numbers include former evil overlords, petty criminals, and even those who simply were not there when a loved one needed them the most. This knowledge of their own flaws tends to make penitents merciful, compassionate, forgiving, and kind. It is hard for them to judge others harshly when they know full well their own capacity for wrongdoing.
All penitents hold similar tenets, regardless of any master they serve.
Atonement. You can’t undo the past, but that does not mean you cannot put a lot of good into the world to balance it.
Forgiveness. If you can fall, so can others. If you can be better, so can others. Never forget this. Never ignore it.
Compassion. You know better than most what can happen when people are at their worst. Strive to create circumstances where they can be at their best instead.
Wisdom. Sometimes the cost of saving someone will be too high. Do not sacrifice the lives and safety of innocents in an attempt to sway the truly wicked.
Add the healing school of magic to your list of herald spells.
At 3rd level when you choose this archetype, you gain the following two Channel Divinity options.
You can use an action to emit an aura of confession that extends 10 feet from you, which benefits you and one other willing creature within the aura. The aura lasts for an hour or until you decide to dismiss it (no action required). The effect also ends early if you or the target fall unconscious, make an attack roll, cast a spell other than those of the healing school, or make a Strength, Dexterity, or Constitution check.
While the aura is active, any words uttered by you or the target are only audible to the two of you. Outside sound can enter the aura, but is muffled; you and the targeted creature have disadvantage on Perception checks that rely on hearing anything but each other while the field is active. Noise other than your conversation passes through the field normally and creatures outside the field can hear sounds on the far side of the area, as well as your footsteps, musical instruments, etc. at no penalty. Magical sensors and creatures besides you and the target inside the aura cannot hear the conversation but pick up other sounds normally.
If you end the effect by dismissing it, you may choose to impart one of the following effects onto the other creature:
As a bonus action, you may choose to exchange hit point totals with another creature within 30 feet that is bloodied and has fewer hit points than you. If this drops you to 0 hit points, you fall unconscious and must make death saving throws as normal.
At 7th level, your commitment to atonement makes you extraordinarily difficult to force into any course of action you do not wish to take. You become immune to charm and compulsion effects, and you have advantage on saving throws made to avoid becoming frightened.
You also gain an expertise die on Insight checks and can always use Charisma when making Insight checks. Finally, while your fatigue or your strife is 4 or less, the penalty you take for it is reduced by one level.
At 15th level, your example compels even the wicked. As an action, or as a reaction when you become bloodied, you can open the eyes of every creature within 30 feet of you to their own moral failings. The effect ends after one hour if you are not bloodied. If you are bloodied, it ends as soon as you receive sufficient healing to no longer be bloodied or after an hour, whichever comes first. Creatures subject to this effect see the full extent of their own sin without the shield of their own justifications or excuses. Creatures with the Atonement destiny are immune to the effects of this feature, as are Celestials and Aberrations. Fiends, Undead, and creatures with the Monster destiny save automatically, but still suffer the reduced effects.
All other creatures with an Intelligence of 5 or greater that enter the area or start their turn in the area of this effect must make a Wisdom save against your spell save DC. A creature that fails its save is knocked prone and stunned, and at the Narrator’s option, may act in a manner that indicates its profound guilt as a result of this newfound clarity, such as sobbing or confessing its sins. It remains prone and stunned until it takes any damage, has to make another saving throw, or until you move further than 30 feet away from it. Creatures that succeed on their saving throw take 4d4 psychic damage and are rattled until the end of their next turn. Once you have used this feature, you can’t do so again until you finish a long rest.
You may also speak words of reassurance to an affected creature and help it to its feet (requiring an action), at which point the effect ends for it.
At 20th level, you become an avatar of mercy and forgiveness. You gain the following benefits:
Eyes of Mercy. Your Lay on Hands feature can now be used at a range of 30 feet as long as you can see the recipient. In addition, you can spend a minute studying a creature and learn the worst thing that has ever been done to it, and what, if anything, could help it move on.
Voice of Redemption. You can cast calm emotions at will without seen components and without expending spell slots.
Hands of Compassion. Any time you touch a creature, it is subjected to a lesser restoration effect. You cannot suppress this effect, but it does work on you. At the start of your turn it automatically affects any creature grappling or grappled by you. Otherwise, to use it in combat requires a bonus action.