Reread Warrior's Apprentice for the first time in ages, fresh off of Shards of Honor and Barrayar, and see parallels between Miles-Arde and Cordelia-Bothari.
When Cordelia is a prisoner of war about to be tortured, she projects onto Bothari as a form of control over the situation, repeating There are two victims in this room, to herself mentally, and telling Bothari out loud, "I believe that the tormented are very close to God. I'm sorry, Sergeant."
Which is when he recognizes her, and is able to mentally supplant Aral Vorkosigan's Rules For Prisoners over Ges Vorrutyer's rules, first refusing to hurt her, and then stopping Ges from doing so.
Bothari's actions in that moment could theoretically happen even if Cordelia said nothing, if he simply looked at her face and Aral's rules kicked in. And Piotr, at Aral's request, making him a Vorkosigan armsman puts him in place plot-wise to do things.
But Cordelia reaching out to him, speaking, empathizing, is what forms the connection between them, leading to Bothari picking Cordelia as His Person To Make Rules. Their senses of identity & personal destinies are intertwined after that.
Almost two decades later, we get Miles & Arde. Miles is a teenager with a lot of cultural & personal baggage that make flunking out of the Imperial Military Academy entrance exams The End Of The World. He's wrapped his entire identity up in getting in & excelling.
When Miles fails the exam, when that path is barred to him, he has no back-up plan. Nothing. He refuses to consider anything. Full on depression spiral, worsened by his grandfather dying. The space adventure starts because Miles wants to help & impress Elena, but if they'd done that a couple years earlier he wouldn't have shattered his imagined future yet, and probably wouldn't have latched onto Arde.
Arde Mayhew is a Jump Ship Pilot. He has implants in his brain to do this work, he & other jump pilots can never truly describe their experiences to non-pilots. His class of ship is being decommissioned, his ship just got sold to a scrapper, he's medically ineligible for updated implants. We meet him holed up in the decommissioned ship refusing to come out, with no plan, just despair.
Miles feels like his entire world is over. Arde's actually is.
Miles empathizes. Miles projects. Miles cannot change the universe to get back his dream, but he can throw himself into finding a solution for Arde. He shoves himself into the situation, digging himself a deeper & deeper hole, never truly considering backing out until they are all literally in an active war zone multiple wormhole jumps away from home.
And one of the first things he does, to protect Arde from arrest, is swear him in as an armsman.
Arde, for his part, is befuddled by Miles' involvement, but latches on too. Miles gives him the chance to keep his calling, and Arde, in turn, risks that very calling ramming his ship into a hostile vessel to protect Miles. During the course of the book, Arde is slowly reshaping his identity from solely a jump pilot to jump pilot & Miles' Armsman.
Our original misfit Vorkosigan armsman is right there judging both of them for it. Arde doesn't understand Barrayar at all. Bothari is extremely pissed about the entire situation; swearing in outsider Arde is only eclipsed by Miles swearing in military deserter Baz Jesek. Bothari eventually comes around on Arde, thanks to the ship-ramming and Arde's reasoning for it, but never on Baz.
Naismiths: insane levels of projection, insane levels of resulting loyalty.