The amount of trust Oswald has in Ed even after everything that happened, to shake his hand making a deal, to let Ed hold a razor blade to his throat as a ploy, to unlock Ed from his cage with a gun in Ed’s hand, and even drop his weapon outside when Ed could easily kill him. All because he trusts Edward will follow through with their deal. If that doesn’t come from some form of remaining love I don’t know where it’s coming from.