I want to visit my sibling in the hospital against their wishes
That could put strain on them. Why go if they don't want you to go?
Because I like to fuck with them.
If they do not want you to go, you need to respect their wishes. Showing up with them saying not to shows that you do not care about them.
I'm surprised they wouldn't want to see their sibling. If they are at the hospital I will go.
It doesn't matter if you want to go, you really have to go by what they say. They might have a reason why they don't want visitors, and you could possibly make them sicker. Why not just have a video phone call instead?