you are right. Regarding revenge:
While betraying the rebels, Raymond accused Rothschild of conspiracy with the rebels to prepare for treason. Rothschild was imprisoned by the king, and the king would only execute him after the wedding, so Raymond could only marry the princess. After he discovered that the princess kidnapped Ian, he changed his mind and provided weapons to the rebels to attack the palace on his wedding day. His housekeeper took advantage of the chaos and killed Rothschild, so his revenge was complete. But his original purpose was not just revenge. Before Ian disappeared, he planned to marry the princess to gain more power. He believed that power was everything.
yes, in fact it was stated in most of the story that he tried to gain as much power to get revenge. even the fact he took in ian was so that he would have the power within the art society, to even marry the princess for power. so yeah, i think its logical to assume his goal to revenge was gaining more power within the society.
Spoiler
Bad grammar warning.
he betray them, they got killed except his friend Henry. and then he engage to the princess, ian was sad about everything and decided to leave but princess found out his relationship with ray, she hired someone to kidnap and kill ian, but ian was sold to a counterfeit dealer by the killer. He then starting to draw counterfeit for a living. Raymond worried about Ian’s suddenly disappeared and searching for him desperately. After he finally reunited with him he realizes his love for Ian. He betrayed the king by helping Henry and the other protesters, they attacked the palace at his wedding day. And he leave everything to Henry and runaway with Ian. The end.