Word for someone who does something they said they wouldn't do
not liar or hypocrite

The word u looking for is Hypocrite

based on the biblical principle proverbs 16: 32, i agree with the author of the passage "better is it that it takes longer to be angry than the strong " to the extent that i share the philosophy that the nobility of heart demonstrates the strength of a person. those who are very proud, get angry easily and show their anger toward others are really weak, but those who are noble and do not constantly obfuscate or contain their feelings of anger, are strong people

it is the background information on the characters and setting explained at the beginning of the story. the exposition will often have information about events that happened before the story began. the exposition is often the very first part of the plot.