Eesh...hope this doesn't negatively effect my Prime deliveries.
Amazon hires tons of people. You might be one of them and in a spot to prepare for your interview. If so, congrats! Your Recruiter may have already prepped you for the actual onsite, but I'll give you some more info to help steer you in the right direction.
Know your Leadership Principle examples and be ready for follow ups
They will probe the living shit out of you. Be sure your answers are bulletproof and properly rehearsed in advance. Some interviews have huge egos (shocker) and take pride in their ability to dig until they finally see the candidate cracking. It sucks, but interviewing is imperfect and some people do this.
Look up the level
No matter the job or the title, be sure you research what level of role you're interviewing for. Amazon won't have someone at a level below the role you're interviewing for on your loop. Ever. If they do, it's sure to rain hellfire as someone messed up somewhere. This should give you an idea how prepared you may need to be and how senior of a role you'll be considered for.
Generally speaking, if you're interviewing for a role and they can't decide if you're a specific level, say an L5 or L6, they will have only L6+ interviewers on your loop in the event you're leveled at the higher level. These interviewers will be tough.
Adapt to poker faces
Interviewers are trained to not react to your answers so they don't telegraph if your answer is headed in the right direction or not. This sucks, but is a very effective way of assessing a candidate without them just telling you what you want to hear. Be prepared for stone cold faces that are unfeeling.
Take advantage of the breaks they offer
They will offer bio-breaks, water breaks, and check in with you a lot. Take advantage of these to try and get your head straightened out. You won't last all day without one.
Watch out for your lunch buddy
Ok, I admit, this one is a little extreme. Your lunch buddy is the person who takes you to lunch. While they aren't an official 'interviewer' they can still throw shade if something negative happens at lunch. Do NOT bad mouth your past employer or talk negatively about anything, in any way. Also, don't order a beer at lunch.
Speak their language
This one will throw your interviewers off. Speak their language. For example, they are looking for your answers to be either below, at, or above the 'bar'. What this bar is representative of the 50th percentile at the company currently. With the idea they want to hire people who are better than 50% of the people working there.
With that, use their language to throw them off when you give your answer. You can follow it up with, "would you say that's raising the bar?". This must be done carefully and respectfully, but can be a way to get at the core of what the interviewer thinks of your answers. Ultimately, this is completely subjective.
Amazon is a great company to work for and the interviews are brutal. You can't possibly prepare for everything and demonstrating some humility isn't a bad thing. If you don't win the first time, you can always (nearly) reapply.