The Fault In Our Stars pt.3

In the last few chapters in The Fault In Our Stars,  Augustus still has his cancer wish, and grants it to Hazel so they can fly to Amsterdam to meet Peter Van Houten, the author of Hazels favorite book. They wanted to meet Peter because he did not finish the book due to the character in the book getting too ill to finish. A few weeks before their trip to Amsterdam, Hazel gets sick and is in the hospital for about a week. Her doctors talked long and hard about letting her continue with the trip to Amsterdam, and agreed she was well enough to go. Hazel, her mom and Augustus packed their bags and enough oxygen tanks for Hazel to survive if anything goes wrong on their trip there.  With knowing this information, what do you think will happen while they are in Amsterdam?