Often, prisoners are pardoned as an act of goodwill, but I'd guess if DJT were to pardon a prisoner it would be an act of spite or because he found some financial benefit. If it's a case where the pardoned person is non violent and not a danger to anyone, and has served a chunk of his or her sentence, I'd call it goodwill.
Pardoning a prisoner is an act of goodwill. The prisoner is being shown compassion--given a second chance to live his life. The prisoner is fortunate that someone in power showed this goodwill toward him - pardoning him for his crimes. There might be a few occasions where someone is pardoned out of spite, but these cases are rare.
The Framers of the Constitution did not regard pardon as a species of high-level gift-giving. They were intensely practical men, who conceived of the pardon power as an instrument of statecraft, and would not otherwise have given it to the president. They understood that the pardon power would be distrusted by the people and abused from time to time, but thought the risk worth taking. For them, pardon was a necessary and functional part of their carefully calibrated system of checks and balances, not a perk of office. Until quite recently that is how the pardon power was understood by our presidents, and they exercised it in a considered and meaningful fashion.
In the past twenty-five years we have lost touch with the rich history of presidential pardoning. Four successive presidents have allowed the pardon power to atrophy, not because there was no more use for it—certainly this is not true since the advent of determinate sentencing - but because they both misunderstood and feared it. The Department of Justice, pardon’s trusted official custodian for more than a century, marginalized and compromised the power; the regrettable events at the end of the Clinton Administration were the direct result of this failure of stewardship.
When a president chooses to pardon someone, it's always on the way out of office. That's because the president knows that people don't support justice applying only to some people and not others. People are usually pardoned for political reasons or convenience, rather than because they are really innocent or there are mitigating circumstances.