These two are a fascinating case, I think. Because Amara straight up abdicated her own throne in Vermeil to marry into the Azurian house, him trying to convince her not to cross the Meridian but ultimately not going after her to force her to return, and his understanding of Amara‘s determined nature, I think their marriage was actually based on love before politics. 

They weren’t trying to unite the two warring countries, given the fact that she gave up the throne to marry and becomes the Azurian Queen instead. Now we don’t know what the political process is of marriage in the realm of MHS specifically, like consort statuses or anything of the sort. Seems like the crown is strictly passed from parent to child but that’s because Amara is gone and the Heir has no other relatives. If it was for solely for political gain, chances are she wouldn’t have to trade her title as Queen of Vermeil, and it seemed her choice was not a universally accepted one in her homeland if Clarissa’s animosity towards her is anything to go by. Amara seems has a theme of following her heart above all else, and isn’t finicky about her dedications. She loved her child and when danger came, she was willing to face the power of an elder dragon for a chance to save them. Arken is a lot like her, but more about holding still and bracing for what’s to come, while she’s more active in her need to protect. 

On Arken’s part, he’s more difficult to quantify because his whole theme is about following his head. He acts with extreme caution to the point it becomes inaction and largely keeps his thoughts to himself. Arken doesn’t speak about Amara, neither positively nor negatively. He just seems to avoid the conversation in general and let comments pass. Up until that pivotal moment after he’s infected with Crystalisis and in the arms of his child, we get a glimpse of how he feels about the situation. He tried to convince Amara to stay, but when she leaves, he fundamentally understood that she cannot be swayed when she makes a decision. He doesn’t attempt to order her or otherwise prevent her from leaving through using power as the birthright king of Azuria. He just continues his plan to get rid of the Rathalos that did not bond during the rite. He’s definitely as stubborn as Amara is.

Even as he tries to execute Ratha V, he’s visibly shocked she would attempt to disrupt the execution. You can see it on his face. And when she is gone, Arken retreats into himself. Amara’s apparent betrayal hit the king harder than I think people realize. He doesn’t defend Amara’s actions, but doesn’t demonizes or really critiques her to his advisors nor his child. (At least not from what I can remember.) Like the heir, he doesn’t blame people for making the obvious assumption. He wants to maintain the Wyverian Covenant and keep Azuria out of danger, and it’s counterproductive to his stance to go and blab about Amara’s plan because that’s going to require breaking the Covenant further and risk the ire of the elder dragon. So he must let her go and be silent. 

He handles the Heir leaving in the same way he deals with Amara leaving: he says nothing. He keeps the truth hidden. While Amara’s leave was loud and undeniable, the heir’s is quiet. While yes, there’s a political reason to keep it under wraps, I think his choice has the dual aspect of protecting his child from scrutiny. The Heir lives in the shadow of Amara’s betrayal, and if it got out that the child of the Turncoat Queen followed her path, the Heir is 100% getting their very own patented traitor name. He loves his child undeniably, though he’s become distant with time. 

He’s hard on his successor, both as a result of the heightened scrutiny on them as Amara’s child and a result of their collective responsibility to the kingdom as royals. They need to be above reproach in every regard and he expects as much. Still, he defends them from the advisors implications, pressing that the Heir will do the right thing for Azuria. I think it’s also layered with internalized hurt from losing Amara, some subconscious defense mechanism to detach. At least that’s my interpretation, so don’t quote me on that. Regardless, in the end, he risks his life to save his only child and puts all his faith in them to save their kingdom, not just as an heir but as a ranger.

Skipping ahead, we see him after Aenshin’s end watching from afar as Amara, still an amnesiac, reconnects with the child she no longer remembers. He watches their child take off and soar to greater heights, and the woman he married walk away once again. She no longer remember their life together or their family, and I don’t doubt he knows this. She’s gets to be a new person now, and he’s a dying man, slowly but surely. I think it motivates him to let go of Amara one last time. He doesn’t chase her. He lets her be. Whether fate brings them back together or keeps them apart, we don’t know and it’s intentionally left that way. I like to think Amara’s memories will slowly return at least for the sake of the heir, but she will never return to power. Maybe she and Arken get to know each other all over again, unburdened. But that’s a topic for another day.

(The fact she and Kris did not die is a miracle, a regular sperm whale bellowing at you can kill you so imagine what a peeved off sky whale that big can do. Memory loss was the best case scenario. Seriously look up what loud noises can do to a person’s body, it’s scary.)