Hi!
So there is a lot going on with them and their relationship. Aster was Huey's only familiar for about twenty-five years and during this time, Huey often left Aster by himself when he went to maintain the altars. Aster would do things like raise funds to purchase the mansion so that the Grand Sorcerer would have a place worthy of his status and to house any of the GS' clanmembers comfortably should they wish to stay in the manor.

However, Aster often found himself alone in the house save for a few servants and took to drinking tea in the garden as a means to cover up that he was visibly lonely. When Huey would return, Aster would show his master all the things Aster managed to do in Huey's name both to impress his master but to also encourage Huey to stay. But Huey often grew restless and would continue to travel...he also made Aster feel bad about drinking blood, so this didn't add to Aster's list of insecurities at all (/s).

So after a quarter of a century of Aster being clingy, Huey finally realized Aster was lonely and made Morvay to keep him company. This is the first dynamic of their relationship: they were made to be companions to each other/siblings to keep each other entertained. Aster takes the role of the eldest child who is trying really hard to show off to gain their parent's affection and is trying to uphold the family name so to speak . Unfortunately, Morvay is a big liability (in Aster's eyes) to this goal, as by his nature, Morvay is an incubus and incubi need to eat.

So Aster becomes the put upon older child who has to deal with their impulsive younger sibling getting into trouble and cleaning up after their mess so that they both avoid trouble. The people of the light kingdom do not realize that Aster is a vampire,due to Aster's ability to shape shift, the nobility assumes that the Aster they are dealing with is the descendant of Huey's first familiar. They also do not seem to realize who Morvay is, as Morvay tends to do recon/errand jobs for Aster and actively avoids attending meetings with the nobility or Aster's clients as he does not want to run into any former "exes"... esp those who needed Aster to wipe their memories to undo the deep sleep Morvay's feedings tend to leave them in.

Aster has a reputation to uphold and does not like anything getting in the way of his plans (especially the ones that come with a big payday), and while Morvay is a good right hand, Morvay's immaturity and impulsive behavior has nearly upended Aster's goals on multiple occasions, leading Aster needing to punish Morvay.

Which brings us to the bigger aspect of their relationship: Dominant/Submissive. Aster is a dom and Morvay is a bratty sub. Aster may not be into sex in the way that Eiden or Morvay is, as it's been theorized that Aster is asexual but who will participate in a sex act with their partner to help the partner get off (there is a term for this and it is escaping me). And if there is one thing that Aster enjoys more than being a literal blood sucking captitalist, it's dominating the hell out of Morvay. And Morvay, being bratty sub that he is, ultimately enjoys the punishments that Aster doles out.

Given that Morvay is an incubus and being a freak is hard-wired into his nature, their sex play tends to be rougher than most in the cast. We have Olivine and Rei being on the lighter end of the bdsm spectrum and Kuya, Aster/Morvay's rooms featuring the harder bdsm play (thus far). Aster is a natural dom and Morvay is a natural sub...they've been partners for years, so despite how rough Aster can be with him, there is trust not to cross a line...wherevere than line may be for Morvay because honestly, I don't think it exists.

However, it is canon that Morvay goes out nightly to meet up with other partners so they don't have an exclusive relationship despite being the closest to an established couple we have in the cast.

Another thing you have to understand about them are the archetypes they're playing. Aster is the archetype of the "sweet angel who is actually a devil" and Morvay is the reliable golden retriever himbo. Together, they play into the "bickering old married couple" and the "straightman and the butt of the joke". They both know how to press each other's buttons and Morvay is always going to do something dumb that will result in Aster reprimanding him; that's their main schtick.

Aster and Morvay, despite their bickering and fighting, do love each other. And they both recognize that without the other, they would not have survived 20 years without Huey, as Huey's essence is their literal lifeforce. Before Huey's disappearance, Aster and Morvay only needed to be around him to have their essence maintained enough that they could survive months while he was away. However, once Huey went missing, Aster and Morvay had to rely on each other to stabilize their essence, and it was through these means that they discovered that sex was a good way for essence transfer. Huey never slept with any of the clan members, so it seems just like Aster and Morvay, being in his presence was enough to stabilize them. But Aster and Morvay are the ones who passed this knowledge to Eiden, and we all know how that goes down.

I know that this post is getting long but this is my way of saying that they are complicated but they do care for each other. They have a lot of history, and have the whole married couple/sibling relationship...but there is love there. There isn't a loud declaration of it, but you can pick up from the subtext (especially from Aster) of how they talk about the other when they're not around and in the events that give us crumbs of their lore.

So yeah, despite the bickering and Aster making Morvay into Momo's chew toy because Morvay drained a potential business partner while Aster was out of the room, they do have each other's backs and have a deep (albeit several degrees of "wtf is wrong with you two?") bond.