I'm not at Expedia but I know a few people who are and I've talked to enough candidates who went through the loop to piece this together.
Expedia has a set of core values they call "Expedia Group Leadership Principles" or something similar. They don't brand them as aggressively as Amazon but the behavioral round is absolutely anchored to them. The main themes I see come up repeatedly:
Customer obsession (travel context). Expect something like "Tell me about a time you built something with the end traveler in mind" or just "customer impact" framing. They care a lot about who the end user is.
Moving fast with accountability. "Tell me about a time you made a decision with incomplete data." "Describe a time you pushed back on a deadline." They want to see decisiveness but also ownership of outcomes.
Collaboration across teams. Expedia has a lot of acquired products (Hotels.com, Vrbo, Orbitz) that are still somewhat separate tech stacks. Cross-functional work and influence without authority come up often.
Inclusion and diversity. At least one question in the loop tends to touch this. "Tell me about a time you amplified a quieter voice on your team" or similar. Prepare something real.
Format: typically 1-2 dedicated behavioral rounds in the full loop, plus behavioral components baked into the manager/hiring manager interview. You're looking at 6-8 STAR stories minimum to be comfortable.
One thing candidates mess up: answering too abstractly. Expedia interviewers want specifics. What was the product, what was the metric, what was your exact contribution. The "situation" part of STAR should be tight; the "result" part should have a number or a concrete outcome.
Don't walk in thinking the behavioral round is easy just because the coding bar is reasonable. That's where some technically strong candidates get cut.