How do I give feedback to defensive people without it going wrong?

You have learned to give feedback in the normal cases, which is already more than most people manage. The ones who still trip you are the difficult and the defensive, and that makes sense, because their walls go up before your words even land. It is not your skill that fails there. It is the fear on their side. A defensive person is usually protecting something, their pride, their sense of safety, their standing. If you can lower that threat, the feedback has room to be heard. Speak to the behavior, not the person. Be plain about what you saw and what you want, without piling on. And give them a moment to react without you rushing to defend your point. Their first flinch is not the final word. Before the next hard conversation, decide the one thing that truly matters and say only that, clearly and kindly. You cannot control whether they get defensive. You can control whether you gave them a truth small enough and warm enough to actually pick up.