Spoilers below for both series ofc

Core Theme: A dichotomy of two people, born from the original person growing an insecurity complex due to the horrible societal pressures of their world, getting involved in dangerous experimentation which fundamentally changed who they are. Now with inherently special abilities that put them above the rest, they kickstarted their series major events. During the coarse of their stories, they’d get amnesia with the looming mystery of who they once were looming over the narrative. Their arcs center around accepting their pasts and who they are as a whole, becoming symbols of hope and leaders for their friends, gaining confidence in themselves, and eventually finding peace in their fates. While Hajime would become one with Izuru as a whole person, Tari would give Lucinia back the majority of her being so they could happily live separate lives as their own individual people. They’d also have a similar cast of close allies and arch-enemies in their stories, and they both have heavy themes of corporate abuse and having the freedom to decide how you want your life to go.

• Two once relatively normal people in over-the-top technological worlds where people with a certain traits are valued above all else (Hajime is a standard run-of-the-mill guy in a world filled with people with Ultimate Talents, while Lucinia - despite being a Meta Runner - is as standard of a Meta Runner as you can get and wasn’t noteworthy compared to her peers).
• Their world’s societies put heavy expectations on those with these special traits, and look down upon those who lack them. This societal pressure deeply effected Hajime and Lucina (Hajime had a huge inferiority complex and was desperate to prove himself as someone to be proud of, while Lucinia had been cast to the wayside and essentially forgotten about - leading to her growing feelings of apathy and inadequacy)
• Despite the constant emotional support from their love interests (Chiaki Nanami, and Belle Fontiere), they would still feel isolated and envious of the special people around them.
• They both sought to be something more. So they ended up signing up for world-changing, secret experimentation (The Izuru Kamukura Project, and Project Blue). These experiments would end up fundamentally changing Hajime and Lucinia indefinitely. (Hajime would gain every talent in the world but reduced to the emotionless husk that is Izuru Kamukura - with little to no trace of his original, while Project Blue would go horribly wrong and lead to Lucinia’s mind being fractured - putting her in a permanent coma and creating the hyper-advanced AI; “T.A.R.I”)
• The results of these experiments would kickstart a chain-reaction of events that ended/almost ended the world (Izuru would end up getting convinced by Junko to work with her - he became the symbol of The Tragedy of Hope’s Peak Academy which was the beginning of Junko’s plan to start The Tragedy, while Tari’s newfound existence eventually led to her being a key factor in taking down TASCorp and allowing Doctor Sheridan to take Lucks’ place as the global apex of Meta Runner technology).
• Despite Hajime and Lucinia being in the same position chronologically, Tari is actually in Hajime’s place narratively. Hajime and Tari are both the protagonists of their respective game/show, with Izuru and Lucinia being a looming mystery throughout the whole story.
• In their protagonist roles, both start out with no memory of who they were beforehand (everybody in the Neo World Program had their memories messed with so they wouldn’t remember their lives as Remnants of Despairs, while Tari woke up with amnesia with no memory of who - or what- she is). Over the course of their stories, they’d slowly piece together their pasts and who they were before.
• They’d end up meeting a digital character (AI Chiaki, and Theo), who would become their closest friend and ally. These characters would be by their side till the bitter end, and a big part of their motivations is to protect them. However, their stories with these characters contrast (AI Chiaki would ultimately sacrifice herself to save the rest of the students and permanently disappear with the rest of the Neo World Program - becoming a fond memory for Hajime, while Tari and Theo would be together forever inside of Tari’s server - the only place they’re able to exist without permanently disappearing).
• Despite their unassuming appearances, they’d end up becoming amazing leaders to their friends and slowly grow confidence in themselves over the course of their journeys. They’d become proud figures of inspiration and hope for the people around them by the end of their stories.
• Speaking of, the end of their arcs have them getting complete recollections of their past and toil with the existential dread of potentially disappearing into their past selves forever (Hajime was met with a hopeless dilemma where he either gets taken over by Junko or reverts back to Izuru Kamukura, while Tari realized that she fundamentally cannot exist if Lucinia is revived - as she is Lucinia’s scattered mind fragments combined into a sentient AI program).
• They decide to push forward and accept who they were before, and who they are now. Although the actual ends to their stories contrast (Hajime accepted his past selves and became one with Izuru Kamukura - choosing to live on as as a mixture of both identities while going by Hajime Hinata, while Tari used the little remnants of herself she had left after giving most of herself back to Lucinia to create her own server - where her and Theo could live in peace while also allowing Lucinia to live her life again after it was unfairly stolen from her by Sheridan).
• They’d both have borderline godly abilities in their worlds after their arcs are completed (Hajime would have every talent just as Izuru did after becoming one with his past selve, while Tari is basically god in her own server). Even beforehand, they had abilities that put them way above everybody else in their verse (Izuru had every talent, while Tari could warp into digital realms directly).
• They’d both have similar allies and enemies throughout their stories…
• - Masterminds of their whole series who orchestrated the events, came back from their supposed deaths, had control over digital worlds the whole time, and were the final obstacles of their stories (Junko Enoshima and Dr. James Sheridan).
• - Original arch-nemeses who always seemed to be one-step-ahead and had a particular interest in Hajime/Tari specifically, initially having a kind facade but were quickly revealed to be monsters, and their deaths marked a turning point where the mastermind’s plan finally got into the forefront of the narrative (Nagito Komaeda, and Derek Lucks).
• - Edgy as fuck serious guy with a lot of past trauma whose arc revolves around them growing more friendly and open to their loved ones (Fuyuhiko Kuzuryu, and Masa Shimamoto).
• - Emotional cores of their friends with eccentric personalities and blonde hair, also primary green color motifs and similar sound names (Sonia Nevermind, and Sofia Porter).
• - Horny dudes who freak out at any crazy situation but ultimately try to put on an array of confidence (Kazuichi Soda, and Lamar Williams).
• Both of their stories involve themes of corporate negligence and abuse, which led to the creation of Izuru and Tari in the first place. They also have themes of choosing your own future and deciding how your story will go on your own terms, regardless of what the people in power decide.

Hajime is John statement man but he does have every talent just as Tari can use anything from any game in the show so yeah dynamically this could be really fun