So, that first episode, huh? With the kidnapping an old man, and the not bothering to call an ambulance when he has a heart attack, and the ripping his prized possession in half right in front of him, and the challenging his panicked and crying grandson to a card game for no reason, and the general mweh heh heh-ing and villain vibes…it feels pretty damn out of left field compared with the sympathetic anti-hero characterization that the show goes with for the entire rest of the series.
And sure, the simple explanation is that the writers tried to cram two manga arcs into 20 minutes while cutting the actual plot and all the explicitly axe-murdery bits and then skipping directly to his lighter and softer post-coma personality, so of course the result was a nonsensical mess. But is there any way to reconcile Pilot Kaiba with rest-of-the-series Kaiba?
Maybe the key is his lack of pupils.