Though Elio's an open person, there are a few secrets that he does his best to keep under wraps - either out of embarrassment or its havoc-inducing nature:
🤫<His emotionally-stunted childhood>: Now that he's able to properly convey his emotions in a healthy manner - which greatly assists him in forming some of the bonds he currently cherishes, he doesn't want to go back to how he used to be; his emotionally-stunted self was soulless - especially with the lack of life in his eyes: someone who went through the motions, lacked any personal interests, and only did what they're told on command. It was like controlling a puppet, and when combined with his then-notable talents in comparison with everyone else his age, he was more of a monster than a human. Every day, he assures himself that he can feel like everyone else, and simply not "faking it". When asked about his childhood, his emotionally-stunted self is purposefully left out - replaced with a fabrication that made him seem more like an average kid.
🤫<Argentium's Aura Cultivation Method>: While Elio doesn't mention it, let alone go into detail about it, his family's Aura Cultivation Method steadily strengthens and refines the main source of his power, and by extension - many of his ever-growing talents. While instinctively knows never to share such a secret with outsiders, it's considered taboo to do so anyways in the Martial Arts world - the art is considered a sacred ritual, and each variation is invaluable to whatever school or clan it originated from - refined over generations and an embodiment of their beliefs and teachings.
🤫<His relationship with Y.H.V.H.>: Because of how much Elio deeply cherishes the Arceus Fragment, being one of its closest friends despite Y.H.V.H. being his superior, he does his utmost to keep their relationship under wraps, as it would put both of them in danger; Elio's standing would be put into question - considering it's already known he's bonded with Zekrom and has an abnormally powerful Zygarde under his command, and there will be multiple attempts to either get close to him for the sake of obtaining divine power, using him as bait to draw out the holy entity, or simply eliminating him using any means necessary by certain dominant powers. Though understanding, due to its inherent awareness of the human condition, Y.H.V.H. was saddened nonetheless as it reciprocated the same feelings as Elio - who's one of the extremely few human friends it's made since the dawn of creation.
🤫<Lucifel the Whiseraph>: Unlike his other Pokemon, Elio doesn't actively employ Lucifel in his battles due to his strengths being otherworldly; from his unique ability to his plethora of signature moves to his refined combat skills, and even the intense pressure his very presence causes - capable of suppressing other powerful Pokemon. In fact, just like with other Angelic Pokemon, Lucifel's species is meant to be secretive as their actions (which are commonly passed off as "an act of God") can severely alter the world if they're not careful - rivaling or surpassing most legendaries and mythicals; it's especially true in Lucifel's case since he's not only inherited the highest rank amongst his species after passing his numerous trials with his trainer but he was blessed by Y.H.V.H. himself - his power now elevated to an entirely different playing field, far surpassing what his kind is normally capable of doing: which says a lot. Though he's on Elio's roster, it's just a formality. Furthermore, should Elio need to summon him as a last resort, he manifests his Pokeball from light particles rather than keep it on his person.
🤫<Team Skull Admin>: While Team Skull is merely a minor team that's more of an annoyance to the Alolan populace than an actual threat, the fact that someone like Elio - who hails from an important family and is well-known for his altruism and battling strength, joining their ranks as an admin is scandalous enough to make headlines in lieu of circumstances and his personal feelings about them. Thanks to his partnership with the Aether Foundation, Lusamine used her influence to keep his membership classified.
