Your falling into a major trap here... you just introduced an Anti Sue. Also going to force vivid random dark fic chapters into the story to pull things off. Your using a pile driver where you need a roofing hammer.
Unnamed Evil Cousin (UEC).... drags the series off into Wangstland, if use as stated. You need to gut the omnicidial, meglomanical, silver age cartoony demigod villan and take the useful core out... yes I'm being somewhat dramatic, but you've given me no real choice here. This guy needs UEC needs to be toned down to Zeke levels or your going to have to have Zeke constantly walking behind a pair of side by side dumptrucks with the lisence plates 'GRIM' and 'DARK'... both leaking clouds of angst and thick, cloying ash respectively behind them. Your not writing the ascention of the GEoM here. Last I checked your writing a character driven multicrossover with a somewhat socially inenpt OC protagonist.
That out of my system... first step: Nuke the AMALGAM take over. It makes no sense if he isn't obscenely corupteed to start with. I have no issue with the basics of this guy... but I can't see the Gods tolerating not Mephisto aymore at that point, if he is turning his avatar into what amounts to Apocolypse with travel plans. Logic fail for me. AMALGAM is only Zeke's enemy by proxy... AMALGAM is Sosuke/Mithril's villian. Zeke is just getting involved via freind and moral connections. Don't make Zeke Mr. Fix-It-Sue in order to validate an anti Sue.
Now for some more productive comments: First, make the UEC older that Zeke. Say late 20s, early 30s, this will let you have him get a good mad on for Zeke. This guy should be Indian pureblood (feathers, not dots), meaning he can have the whole chip on his shoulder thing being his starting flaw. He is wiser than Zeke (read older), not a half breed (gonna need a warped take on some tribal legends/ missing the point of what Raven actually does), A 'Me! Glorious ME! morality complex.
Basically where Zeke has issues because he is kit bashing his world view and social interaction filters. He doesn't really get quite enough time to congeal something solid (social structure, interaction wise) before he moves and new conflicting stuff is thrown in. Forcing him to take things apart and alter everything to work with the new stuff. Which is exactly why he doesing all these prototyping and enchanting thingies. It keeps with that mind set and the results are so much more easily read and consistant. Lets him have that control that keeps him sane. His compulsive documentation of work should fate him a legacy book. The kind of thing people fight/quest for long after he is gone. It helps Zeke is slowly unlocking his whispered abilities in little pieces, without knowing it,
UEC was a hard core tradtionalist. The kind of guy who make progress it baby steps not leaps. Everyone thought he was talented, but more skilled filler then anything else. He is rigid thinking, has difficulty grasping new concepts without long steady effort at chipping away at the concept. Though its his forever once he does so. Feeling he really needed learn that there was a box to think outside of in the first place, he was assigned to teach Zeke something mystical for a month or three. This caused him to switch tracks... instead of derailing his thought train. As planned he learned from Zeke as Zeke learned from him. Though different lessons.
UEC learned that not only is there a box... but many different types of boxes. He had Zeke start explaining how he reached conclusions half way through the lesson. Zeke explains with answers that draw from dozens of random sources to fill in the gaps. UEC can see how he got their post explaination... he just never thought of thinking that way, at all. Seeing Zeke's progress UEC starts to learn all kinds of previously useless to him things and he starts making real progress.
In fact, even with Zeke's learning curve UEC thinks they are about evenish until he is drawn out of his studies to watch the Tag game of Planetary Doom! Research followed by panic ensues... particularly when he gets to that thing about the harem apparent forming. His parents are going to be relentless about him getting married now. Blarg. So he runs off to Japan (pets in tow), quickly decides copiing Zeke isn't going to help him advance and ends up going after the untapped source of knowledge... all those villian that keep doing stuff with spirit magic he hasn't heard was possible. So he seeks out a dark, but not instantly self consumming power and markets himself to the villians as a local consultant/cultist.
So he begins working for SM villians and other mystic evil types. Always looking for openings to send those corrupt idiots to the shadow realm or whatever. His goal is knowledge and research not concuring... a girlfriend would also be nice. Keep the parents at bay. Thus begins a career of 'pretending' to be 'evil'. Keep him away from Beryl and the Doom Tree and have him skip on those blood thristy 5 Witches and Galaxia. Most of the rest non movie villians are more annoying jerks that omnicidal.
Of course he is as socially broken as Zeke in his own way. Though he hides it better, he is charisma smoozer man and sees people as tools. If he ever meets Rei's dad they will deaath match as there can only be one. He just doesn't get people... to the point he doesn't realize that what he is doing isn't obvious to those in his mystic circles. UEC thinks that he is doing good by running insider damage control, subtile assassinations of the corrupt, and of course yoinking perfectly good research.
The reason UEC keeps so many pets is post Zeke he decided to raise his own spirit totems. He likes spirit magic and having loyal powerful spirits exclusively is awesome sauce. When he meets the Animal Eye group he'll be enthralled... a way to make smarter more powerful bodies for his pets (he does ask first and explains what he is doing). The ability to analize people's dream while they are awake is icing.
So he randomly battles Zeke (good cover and training), makes 'evil' drama queen speaches and basically makes a reoccuring villain out of himself. Useful for all types of things. Amuses rather than enrages the gods tolerating his patron. Feeds his parton. Works in thematically. Add in him sending update letters home and his parent ignoring the context and concentrating on the fact he is dating now gives great fodder for the late reveal.
GRIM DRAK onmicidial conqueror... not so much. Pick at this.
Unnamed Evil Cousin (UEC).... drags the series off into Wangstland, if use as stated. You need to gut the omnicidial, meglomanical, silver age cartoony demigod villan and take the useful core out... yes I'm being somewhat dramatic, but you've given me no real choice here. This guy needs UEC needs to be toned down to Zeke levels or your going to have to have Zeke constantly walking behind a pair of side by side dumptrucks with the lisence plates 'GRIM' and 'DARK'... both leaking clouds of angst and thick, cloying ash respectively behind them. Your not writing the ascention of the GEoM here. Last I checked your writing a character driven multicrossover with a somewhat socially inenpt OC protagonist.
That out of my system... first step: Nuke the AMALGAM take over. It makes no sense if he isn't obscenely corupteed to start with. I have no issue with the basics of this guy... but I can't see the Gods tolerating not Mephisto aymore at that point, if he is turning his avatar into what amounts to Apocolypse with travel plans. Logic fail for me. AMALGAM is only Zeke's enemy by proxy... AMALGAM is Sosuke/Mithril's villian. Zeke is just getting involved via freind and moral connections. Don't make Zeke Mr. Fix-It-Sue in order to validate an anti Sue.
Now for some more productive comments: First, make the UEC older that Zeke. Say late 20s, early 30s, this will let you have him get a good mad on for Zeke. This guy should be Indian pureblood (feathers, not dots), meaning he can have the whole chip on his shoulder thing being his starting flaw. He is wiser than Zeke (read older), not a half breed (gonna need a warped take on some tribal legends/ missing the point of what Raven actually does), A 'Me! Glorious ME! morality complex.
Basically where Zeke has issues because he is kit bashing his world view and social interaction filters. He doesn't really get quite enough time to congeal something solid (social structure, interaction wise) before he moves and new conflicting stuff is thrown in. Forcing him to take things apart and alter everything to work with the new stuff. Which is exactly why he doesing all these prototyping and enchanting thingies. It keeps with that mind set and the results are so much more easily read and consistant. Lets him have that control that keeps him sane. His compulsive documentation of work should fate him a legacy book. The kind of thing people fight/quest for long after he is gone. It helps Zeke is slowly unlocking his whispered abilities in little pieces, without knowing it,
UEC was a hard core tradtionalist. The kind of guy who make progress it baby steps not leaps. Everyone thought he was talented, but more skilled filler then anything else. He is rigid thinking, has difficulty grasping new concepts without long steady effort at chipping away at the concept. Though its his forever once he does so. Feeling he really needed learn that there was a box to think outside of in the first place, he was assigned to teach Zeke something mystical for a month or three. This caused him to switch tracks... instead of derailing his thought train. As planned he learned from Zeke as Zeke learned from him. Though different lessons.
UEC learned that not only is there a box... but many different types of boxes. He had Zeke start explaining how he reached conclusions half way through the lesson. Zeke explains with answers that draw from dozens of random sources to fill in the gaps. UEC can see how he got their post explaination... he just never thought of thinking that way, at all. Seeing Zeke's progress UEC starts to learn all kinds of previously useless to him things and he starts making real progress.
In fact, even with Zeke's learning curve UEC thinks they are about evenish until he is drawn out of his studies to watch the Tag game of Planetary Doom! Research followed by panic ensues... particularly when he gets to that thing about the harem apparent forming. His parents are going to be relentless about him getting married now. Blarg. So he runs off to Japan (pets in tow), quickly decides copiing Zeke isn't going to help him advance and ends up going after the untapped source of knowledge... all those villian that keep doing stuff with spirit magic he hasn't heard was possible. So he seeks out a dark, but not instantly self consumming power and markets himself to the villians as a local consultant/cultist.
So he begins working for SM villians and other mystic evil types. Always looking for openings to send those corrupt idiots to the shadow realm or whatever. His goal is knowledge and research not concuring... a girlfriend would also be nice. Keep the parents at bay. Thus begins a career of 'pretending' to be 'evil'. Keep him away from Beryl and the Doom Tree and have him skip on those blood thristy 5 Witches and Galaxia. Most of the rest non movie villians are more annoying jerks that omnicidal.
Of course he is as socially broken as Zeke in his own way. Though he hides it better, he is charisma smoozer man and sees people as tools. If he ever meets Rei's dad they will deaath match as there can only be one. He just doesn't get people... to the point he doesn't realize that what he is doing isn't obvious to those in his mystic circles. UEC thinks that he is doing good by running insider damage control, subtile assassinations of the corrupt, and of course yoinking perfectly good research.
The reason UEC keeps so many pets is post Zeke he decided to raise his own spirit totems. He likes spirit magic and having loyal powerful spirits exclusively is awesome sauce. When he meets the Animal Eye group he'll be enthralled... a way to make smarter more powerful bodies for his pets (he does ask first and explains what he is doing). The ability to analize people's dream while they are awake is icing.
So he randomly battles Zeke (good cover and training), makes 'evil' drama queen speaches and basically makes a reoccuring villain out of himself. Useful for all types of things. Amuses rather than enrages the gods tolerating his patron. Feeds his parton. Works in thematically. Add in him sending update letters home and his parent ignoring the context and concentrating on the fact he is dating now gives great fodder for the late reveal.
GRIM DRAK onmicidial conqueror... not so much. Pick at this.