"I'm sorry, Scarlet. Killing sinners is my job."

In the world of I'm the Grim Reaper, Satan creates Grim Reapers by taking the soul of a sinner from Hell and offering them a contract - return to the world of the living as a Reaper and kill one sinner each day, or fail and return to Hell to suffer. Brook, the second of the three currently active Reapers, is a rare exception to the norm - he was never a sinner in the first place. Instead, he wandered into Hell from Purgatory looking for purpose, as he found his afterlife to be unbearably empty, so Satan allowed him to trade places with a sinner and become a Reaper, which he's been doing for over a century.

Grim Reapers draw their power from the demon that Satan binds to them when he sends them back to the world of the living. While most Reapers risk their demon taking over if they become overcome by emotion, Brook lacks this weakness - since he's not a sinner and won't be sent to Hell even if he fails, Satan doesn't typically care if he fails his contract, and even then his absolute worst case scenario is returning to Purgatory. As a result he's never had trouble controlling his emotions or risked being overcome by his demon.

I'm the Grim Reaper is created by GRAVEWEAVER and can be read here.

Brook scales to another Reaper named Scarlet, whose respect thread you can find here. He's shown to be able to completely overpower Scarlet before she pulls out her demon, and was explicitly going easy on her before the demon came into play.

Rollover a feat for for the chapter source.

Strength

Rather than generating a weapon like some Reapers, Brook typically fights by enveloping his fists with his demon's energy to increase his physical power.

• Throws Scarlet with one hand across a large room hard enough to crater a concrete wall
• Tosses Scarlet
• Snatches a vaulting Scarlet from the air and slams her into the ground hard enough to shatter it
• Jumps above a floating Archangel without her noticing and kicks her into the ground hard enough to kick up a huge cloud of dust
• Tears Scarlet's arm off
• Rips Scarlet's leg off
• Snaps Scarlet's neck
• Charges Scarlet and shatters her scythe
• Crushes Scarlet's scythe
• Catches Scarlet's scythe
• Blocks an attack from Scarlet

Durability

Reaper durability is a little odd. Since Brook's body is just a flesh puppet created by Satan to serve as a vehicle for his soul, he can't be killed by damaging it - Reapers are already dead, so no matter how much the body is harmed Brook can't die. However, damage can still impede the function of the body, so a sufficiently damaged Reaper will no longer be able to fight, and will thus likely fail to maintain their contract with Satan and be damned to Hell.

• Unconcerned by a bullet through the head
• Shrugs off a demon-enhanced punch to the face from Scarlet
• Gets stabbed in the throat and has his torso carved up by Scarlet's demon and is still fighting
• Impales his forearm punching an Archangel's blades, then just shatters them and pulls them out
• Still 'alive' when reduced to just a head
• A bullet won't kill a reaper. Even being chopped up into pieces won't put them down
• Removing a Reaper's heart won't kill them

Agility

• Gets behind Scarlet and smashes her head into the ground faster than she can react
  • Scarlet is fast enough to jump in front of a bullet after it's fired
• Kills a woman's bodyguards before she notices
• Catches up to Scarlet with a jump
• Lands on his feet after being thrown by his ankle, until he falls over because his ankle's been crushed
• Avoids attacks from Scarlet's demon at close range
  • Scarlet's demon is fast enough to intercept bullets
• Dodges a sudden attack from Scarlet's demon

Sinner's Mark

• Sinners are marked with an X in a Reaper's sight, making viable targets visible at a glance
• The mark doesn't give any details as to the nature or scale of a sin, and a serial killer will appear the same as someone whose greatest crime was to steal a snail a day from the restaraunt she worked at for a few years
• What counts as a 'sin' is based on the values substantiated by humanity
• The sinner's mark doesn't care about circumstance or morality, only that you've committed a sin

Hell

When a Reaper kills their daily sinner, they are transported to Hell to witness Satan judging and punishing their victim.

• Time moves slower in Hell, and Reapers can't die there
• When seen from the outside, the trip to Hell and back only takes a second or two
• Satan restores his Reaper's bodies to peak condition every time they return to Hell
  • Satan restores Brook from just a head
• A Reaper can't leave Hell unless Satan allows it

Misc

• Reapers don't need to eat or sleep, and Brook has been one so long he sometimes forgets that mortals do
• Has a camera phone