There's this Buddyfight x Vanguard (not G or V) one-shot which starts with an Author's note, and Author-San basically confirms that Author-san hopped onto the fandom headcanon that Kaichi gave birth to Tasuku (it implies that Buddyfight takes place a dozen years into the future). I even read a Shield Hero x Vanguard fic on ao3 that literally shows Aichi as nearing labor. And I stopped somewhere, but I know it's Tasuku and sometime after the giving-birth scene. This one explained it away with the red eyes being from Toshiki-senpai's side of the family. Honestly, in that AU, why would Tasuku be part of the Buddy Police? He has a doting mother (like Shizuka, who's not annoying about it like Emi is), a protective father the likes of Smaug and his hoard, both parents present all his life, a (doting) grandparent, a huge extended family consisting of the Vanguard-anything cast (and maybe the orphanages), a secure, love-saturated environment, experience in another cardgame which he can apply to Buddyfight, and, well, a perfect life.In the case of the doting/overprotective parents, they'd want him to be safe, and they know that police work is real dangerous. Tasuku, Kaichi or not, is generally too hype to do officework all day. Plus, without being a victim of that Disaster thing (I didn't catch that many backgrounds in the anime), he would be a happy, well-rounded person, allowed to act his age (though he's never stupid). For all we know, he would be more sociable with being around so many (trusted) people all his life. Pick up on cues better. be a more stable person. If it came to be part of the dark side, he'd be like that "f**k this s**t, I'm out!" vine. You know, since everyone was possessed by or encountered a dark-side person. Plus, both parents were possessed by an evil power, so he'd get all the emotional maturity he needs. He already has the affirmations, the affection, all the basic childhood experiences, anything he could want to stay in the light. Tasuku would be a stronger anything for it. Maybe even learn to crack a joke or dance or sing or something from the dozens of honorary family members available!
Also, you can totally have a different first meeting with Jack! That’s what I posted!