Hey, have you realised just how many times Dio changes his mind on whether he’s going to kill Jonathan personally or just assume someone else will for him? E.g. Ogre Street, Bruford and Tarkus. I think Dio was really conflicted about his feelings for Jonathan so, while he acts rather casual about finally killing Jonathan so he can get his hands on his fortune/rule the world, when Jonathan actually dies, Dio’s actually shocked. It just reminds me of how fucked-up a relationship they really have.

highdio:

I don’t see it that way at all although agree, their relationship’s real messed up.

That
first part, that was a matter of respect.  From the time he showed up
as a kid at the mansion, Dio thought of Jonathan as weak/inferior.  It took Jonathan going through a whole series of tests for Dio to
respect him enough to want to kill him himself.  And that’s a huge theme
in PB – Araki talks about Jonathan as a “reactive” character, about him
being forced into becoming a hero by Dio’s attacks.  The villain makes
the hero.

That second part, you see that idea a lot about Dio being sad when he finally killed
Jonathan, which is cute as a headcanon/fandom thing.  But I still think in canon Dio’s
much more shocked at his own fate – being a disembodied head
in the arms of a dead man on board a sinking ship that’s also exploding –
than he is at Jonathan dying. 

Had Jonathan died and Dio escaped with the body, Dio wouldn’t have been too broken up about it.  The opposite actually, that was the plan.  If anything, in that final scene Dio’s shocked that Jonathan had the nerve to die before Dio could talk him into letting go of him, that’s actually what he’s saying in those panels –

it’s
Dio trying to find a way out of his own doomed fate.  Jonathan dying
means Dio’s own death sentence, that’s real significant when you try
to understand that scene.

I mean, I think Dio
respected and loved his brother at the end of Phantom Blood in his very
weird way, but that respect went hand-in-hand with killing him. The two
thoughts weren’t conflicting.  Dio had no problem with killing Jonathan, he just didn’t want to die with him.