Monsters attack party members when I have aggro

[kikix12]

And even before that, you'll see the more common pattern of bosses who have a specific attack that's programmed to go to a random party member(...)

Except tanks. It cannot be called fully "random" if it excludes the person that is top of the list.

Though I don't know whether it excludes "tanks", as in the role, or "tanks" as in the person with highest enmity. Probably highest enmity...but yeah. There are attacks that go or don't go after specific roles.