He nurtured in him a strong craving for revenge from those criminals.

Revenge : the desire to repay an injury or wrong.
Mercy : compassion or forgiveness shown towards someone whom it is within one's power to punish or harm.
Pardon : the action of forgiving or being forgiven for an error or offence.
Pity : the feeling of sorrow and compassion caused by the sufferings and misfortunes of others.
Forgiveness : the action or process of forgiving or being forgiven.

Antonym of Revenge is Forgiveness