How can one be absolved from the wrongdoing of harming and defaming an introverted and eccentric colleague?

One must repent to Allah and regret what has happened, and seek absolution from those who were wronged, for the Prophet, peace and blessings be upon him, said: "Whoever has wronged his brother concerning his honor or anything else, let him seek his forgiveness today before there is no dinar or dirham." Repentance has four pillars: abstaining from the sin, regretting it, resolving not to return to it, and seeking absolution from the rightful owner if the sin pertains to the rights of a human being. The harm caused to the wronged person should be remedied by praising him and commending him publicly, and refuting any evil that was attributed to him.