lasting trust absolutely can come from choice, but chance... that's where it gets muddy. The choice part is their entire dynamic, right? Draco choosing to look past his prejudice, Hermione choosing to see the humanity in him after everything. Every act of defiance, every shared secret, every moment of reluctant alliance is a choice that builds a foundation. That’s the core of the slow-burn trust for me—it’s earned, brick by painful brick, through conscious decisions that go against their entire upbringing.
But chance? It’s the catalyst, never the glue. Like, chance throws them together in a hallway during the war, or forces them into a Ministry mission as adults. It creates the proximity, the situation where they have to interact. But if the trust that forms from that is based only on circumstance—like, 'we’re stuck in this safe house so I guess I have to rely on you'—it evaporates the second the external pressure lifts. Lasting trust needs the follow-up choice to stay, to be vulnerable even when you don’t have to be.
I read one fic where a chance encounter in a potions lab after the war started everything, but what made it stick was Draco, months later, choosing to confess a secret that could ruin him, not because he was forced to, but because he wanted her to know. That shift from chance-forced interaction to deliberate, risky choice is where the real, lasting trust gets forged. The chance event is the spark, but the series of choices is the fire you keep feeding.