Psychopaths are people who have a very low level of empathy and guilt. They often have no problem hurting other people, and they don't feel any remorse or guilt for their actions.
Reassuringly means in a way that makes you feel better. When you are reassuringly told that everything will be okay, it can help you to relax and to feel less worried.
To renege on a promise is to break your word and refuse to do what you said you would do. This can be a very harmful thing to do, because it ruins trust.
Reoffending means that someone commits a crime again after they have been released from prison or jail. This can happen for a variety of reasons, including a mental illness or addiction.
A philanthropist is someone who is concerned about the well-being of other people. They often give a lot of their money to charity, in order to help others.
Irredeemable means that someone or something is completely unable to be redeemed. This means that they are not worth saving, and there is no way for them to get better.