I HC that Yuichiro was just starting out in Sci-labs after graduating when Dr. Tadashi Hikari died. Like Lan’s relationship with him, his father was the world to him and he would take his death hard.
He shut down. He still managed to accomplish his tasks but Everything he did lacked his usual passion. His usual drive and out of the box way of approaching a problem. He was completely on auto pilot. His new co-workers would offer condolences and try their own way of cheering him up, but no matter what they did he was still this… empty shell.
(Whether the following was before they started dating or after i don’t know)
Haruka made sure he was never alone. Took it upon herself to watch over him. Comfort him. Never tried to take him out to cheer him up, or did anything special beyond making sure he was properly fed. She was just… there. When he talked she listened. When he cried, her heart broke seeing him in pain and she would gently remind him that he was not alone and that he was not without people who loved him.
(I have no idea where this came from, I was just trying to figure out how Haruka got with Yuichiro despite his obliviousness.)
aww that's sweet, though some timeline stuff is inaccurate
Tadashi definitely died after Yuichiro and Haruka married. Actually, considering he knew Lan and Hub, it's possible he died shortly after they were born. Whether he helped Hub turn into Megaman is up to interpretation because it's not really clear, but regardless his death definitely happened after Yuichiro established himself at SciLab
I do agree about him potentially shutting down though, but not really in a "shut down" way...
See, if Tadashi's death (along with the weight of him digitizing part of his being to hold off Alpha) and Hub's diagnosis with HBD happened in rapid succession, it's possible that Yuichiro was just SUCKER PUNCHED with tragedy after tragedy
He did mourn his father, and felt like he lost his best friend (because my personal hc is he got really close to his dad after his mother died when he was a child) but then one his babies starts getting sick...and sicker...until the doctors say his heart can't function anymore
But instead of shutting down from all the grief, Yuichiro acted
He couldn't do anything for his father, but he could somehow save his son
And that's the shut down I'm talking about--not a shut down as in he stopped functioning, but a shut down where he didn't think of anything else and just kept working because he had to make sure Hub's soul was saved. That must have taken so much time and dedication
I think Hub's death did put a strain on his and Haruka's marriage. Haruka had an idea of what Yuichiro was doing, but from an outside perspective he pretty much buried himself in his work and neglected her and their other son.
I think she did confront him and begged him to stop and come home. I think he lashed out and said he couldn't because he had to save him! He had to save his baby! And that's when she finds out the extent of his plan with his Navi project...
Eventually, with a lot of time and patience and Haruka coming to lab to bring his clothes and food (because gosh dang it Yuichiro you can't save Hub if you're half fucking dead!), the two have a more emotional heart to heart and they patch back together their relationship.
By then Megaman would be on his way to being functional so Yuichiro could make more time to spend with Lan. This is also when he brings Lan to the lab to look at his "future Navi"
Anyways, I made this more about Yuichiro's relationship with Hub than his dad, so I'll just say that Yuichiro never really properly mourned Tadashi because of everything going on afterwards. This leads to more of his regret and guilt that he felt during BN3 because he felt like he failed as his father's son when it came to the Alpha project. He still misses him terribly, but he knows his father is still looking out for him in some way (after all, he did save Megaman in BN3)