Edelgard and Hubert have both known each other since they were very young, when Edelgard was four and Huber was six. Hubert was assigned to protect Edelgard as a child, as that is the duty of the von Vestra household. However, Hubert became convinced this was beyond duty due to how strongly he felt about Edelgard and his attachment and protection of Edelgard became something intensely personal.
For the entire pre-timeskip, and within multiple alternate routes, Edelgard and Hubert are the only ones who can share the full extent of their knowledge with one another.
When Edelgard was eight and Hubert was ten, Edelgard's Uncle Arundel defected from the kingdom and took Edelgard with him. A ten year old Hubert left the city and fought off soldiers for three days in an attempt to rescue Edelgard, but did not succeed.
In Hubert's supports with Byleth, he will threaten them because he worries about whether they have Edelgard's best interests at heart.
In Hubert's supports with Ferdinand, he says that Ferdinand is far beneath Edelgard and that he can never hope to even think about being comparable.
In his final A support with Edelgard, Hubert confesses he loves her.
In their final relationship card at the end of the game, it will say they retired peacefully together and that they may never have spoken about the full depths of their love for another.
Hubert leaves a letter in case of his and Edelgard's death, which urges Claude to take responsibility for the sacrifices Edelgard has made in an attempt to create a better world.
Hubert is the one most concerned with Edelgard's transformation choice during the final battle and worries about the reversibility of it.
- “The sensation of loss that overcame me on that day defies all description. It was as horrific as if I'd lost all my limbs. I left the city in a mad rush to rescue you. My father sent soldiers to capture me. I fought them off for three days, but they did finally manage it. Of course, I was only ten. I never would've reached Fhirdiad.”
- — Hubert.
- “I would make any sacrifice to support Lady Edelgard. It's a shame you've never experienced such devotion.”
- — Hubert.
Many fanfics focus on the life of Edelgard and Hubert after the Crimson Fire route, as its possible for both of them to retire together in that route, and as its the only route where the two both live.
However, it's still popular to write fanfic exploring the more tragic routes for both characters.
There's also many stories that cover their childhood together, as there is a lot of unexplored potential.
There is some occasional friction with Ferdibert and Edeleth shippers, largely due to the game system of multiple canon endings and arguments over which is 'most canon' or 'most deserving' of being canon. However, there's many people in fandom who also multiship, or ship both and also OT3 variants of both ships.
- Edelgard and Hubert have unique voice lines for eating together and working together. Hubert also has specific voice lines for being healed by Edelgard or watching Edelgard successfully launch an attack