I've seen several Dr Who fans hate Twelve for what happened to Bill in World Enough And Time. And obviously you can hate characters for any reason at all (as long as you're not dicks to real people about it). But I really don't follow the logic of how it's his fault?

Like the episode itself plays with the idea of blaming the Doctor, with the hard cut between Bill entrusting her safety to him and the aftermath. But as for what actually happened: team TARDIS answered a distress call, and the Doctor stepped in as soon as things got actually dangerous. The whole episode could've just as easily happened the same way if Missy wasn't there. The way it turned out was bad luck (to put it mildly).

I just don't see how the Doctor was really at fault, and the episode might even have been a bit more interesting if he was more at fault. His companion coming to harm directly due to him trying to make the Master a better person (rather than coincidentally happening at the same time) is a really tragic idea. (That's not me saying that the series 10 finale isn't already interesting or tragic. I adore it.)