I don't think that Jamie ever met Charles in the earlier time line. His antipathy towards Charles is likely because he knows that it was Charles that authorized the raid on Villa Mare Vista and believes that he ordered the killing of Croal. I doubt that he knows that Loka took over the raid without Charles's knowledge and told Darion Trapp to stay out of it, he would take care of it.
I'm not sure that Charles, in his isolation and in his fight against the madness of disunion, was aware of just how much of the Sh'ônfenn had been subverted to his own purpose by Loka. Did you notice that of the 12 Red and Black that we know survived, only Charles sided with Jamie and Nic and how surprised he was that the other 11 didn't. The 11 that went with Hippolito were evidently Loka loyalist. As was Geoffrey of Batwig. Although, he may just been miffed that he was passed over for elevation to prince.
Anyway it should all become clear once we get to Part 4 and the end of a very long cliffhanger.
Since Jonas was human, he couldn't have been Charles's mate. Please see my thought's about Charles's age at the wiki