Giddon acutely remembers the first few trips he took with Po alone. It had been decided out of necessity: Katsa wouldn't go with him, and Raffin, or Bann, or Oll had been needed elsewhere. Helda had been with Bitterblue. Giddon had tried to be civil.
He had expected fights, somehow, but Po denied him. He had been disgustingly fair and gentle, until Giddon felt ashamed for trying to start so many arguments. He remembers, early, thinking Po had a better sense of himself than he did, and joking that Po's Grace had some alternate component that made him inhumanly decent. He had forgotten that this made Po go still and stiff, but he remembers it now.
The thing is, trips with Po had become important. Giddon liked them, even if he had increasingly suspected Po was lying about a lot of things, especially his Grace. Sometime around the second or third short trip for small business, he'd worked out Po didn't hold a grudge against him for having wanted to marry Katsa-or for having behaved badly about it. ("That is between the two of you. Katsa isn't mine to control like that." Giddon rather thought it got to the heart of the matter.) Po was a good hunter, almost as good as Katsa. They always had good food, and he had an uncanny knack for finding caves to shelter in when an ally's house was not available. Po charmed, and he badgered, and between them they could cover any possible rapport needed. He made Giddon think. Giddon thinks Po made him grow up.
He has time to think, on the way to Estill, and on the way back to Bitterblue City. And what he decides is most important, more than anything else about lies or truths or Graces, is that he misses his best friend, and trips together where he becomes a better version of himself. If Po's Grace is what has helped spur that, then he would forgive it a thousand times over so he can become a better person yet again.