The past perfect tense is 'had forgiven'.
The present perfect tense of "forgive" is "have forgiven" or "has forgiven." This tense indicates that the action of forgiving has been completed in the recent past or continues to have an effect on the present moment.
The simple past tense of forgive is forgave.
Forgave does not have a past tense. It is the past tense of forgive.
Existed is the past tense. The past perfect tense is had existed.
The past tense is bled, and the past perfect tense is had bled.
The past tense of sit is sat; the past perfect tense is had sat.
The past perfect tense of hope is had hoped.
The past perfect tense is had set.
The past perfect tense is had submitted.
The past perfect tense is "had confronted".
The past perfect tense is had rung.
The past perfect tense is had burned.