I'm Sorry.... I'm so sorry...
Definition of PENITENCE:
The quality or state of being penitent: sorrow for sins or faults.
When placed on the Shelf of Penitence in episode 24 of Adventure Time titled “What Have You Done?”, Ice King’s Crown sobs and apologizes to someone, most likely Ice King. What the crown is apologizing for was not state but be inferred that it’s remorseful for the state it’s left the Ice King in.
In “Finn the Human” the alternative world Marceline says that the crown, in a state of grief, froze the world when Simon died trying to stop the bomb.
Ice King’s Crown seems to care for him deeply. The crown is established as a cursed crown many times through the show but it seems that the crown itself is not evil.
This calls into question the nature of the crown and the actual curse itself.