godan verb (-u)
Used for giving something in return for a good deed, effort, or kindness. Often implies a positive return.
See also: 報いる
彼の親切に報いるために、何かお礼をしたい。
I want to do something to repay his kindness.
My efforts were rewarded and I passed the exam.
godan verb (-u)
Used for returning harm or an injury, often in a negative context. Less common than the positive sense.
彼は侮辱に報いるために、相手を訴えた。
He sued the other party to retaliate for the insult.