thinking about how arthur shoved a dagger into his own throat to save john from the king because john's his friend and he loves him. and then when arthur finally collapses beneath all of that pain and grief and guilt he's carried for years john saves him from being buried and then saves his life in the mines and arthur believes it's because john feels the same. they're friends and they love each other so of course. of course you would do anything to save the one you love.

so he trusts him. he trusts him all the way to new york and doesn't think for a moment that there could be something amiss. that john, his best friend who killed the last person he loved and whom he himself almost willingly died for, is lying to him. again.