Transcript for Prince William, Prince Harry greet well-wishers ahead of royal wedding
The princes we've all been waiting for. Look at the excitement. Reporter: All smiles. Prince Harry along with his brother, William, greeting throngs of well wishers outside Windsor castle. Looking at ease before his big day. Many in the crowd have been camped out for days, hoping for this very moment. The 33-year-old prince taking extra time with his youngest fans. And even accepting a teddy bear. Before heading back inside the castle. Do you think Harry might an bit nervous the night before his wedding on the world stage? Actually he seemed incredibly relaxed tonight. How are you feeling tonight? Reporter: Bride to be Meghan Markle and her mother were seen today returning from tea with the queen. They'll spend the night at T cliveden house hotel along with some of Meghan's closest friends. How are you feeling, miss Markle? Wonderful, thank you. Obviously it's quite daunting flying to London, then meeting the queen a couple of days later. But obviously the queen really wanted to meet Doria, she wanted Meghan's family to feel welcome here. Reporter: Meghan's mother on a royal meet and greet since her arrival Wednesday, meeting with prince Charles, his wife Camilla, and William and Kate. Doria Ragland is the only member of Meghan's family who will be in St. George's chapel for the ceremony. Meghan's father is no longer attending the wedding, reportedly recovering from heart surgery and possibly embarrassment after allegedly staging Paparazzi photos. The palace announcing prince Charles, Meghan's future father-in-law, will walk her down the aisle instead. I guess he never really had a daughter he'd be able to walk down the aisle. I think it's nice he's going to get to do that for Meghan. I was told as soon as Meghan realized her father wasn't going to be coming to the wedding, her thought immediately turned to prince Charles. I think a lot of people might find that surprising. Her mother Doria was the front runner to step in and do it. But clearly Meghan feels that the royal family is a family that she already feels very comfortable with. She clearly wanted Charles to do it. I'm sure it will be a very special day for everybody. Reporter: The prince and his princess to be departed their final rehearsal this morning. The next time they'll likely see each other will be at the chapel. The very same one where Harry was christened 33 years ago, seen here in the arms of his mother, at just 3 months old. Prince Harry has grown up on the world stage. Through life's joyo Q and the sorrows. Who could forget the heartbreaking image of the 12-year-old prince walking with his beloved mother's casket. Losing your mother at such a yog age does end up shaping your life, massively, of course it does. For generations royalty has held themselves in privacy. Here Harry has talked openly about the loss of his mother. Reporter: Prince Harry revealed his feelings in a recent bbc documentary entitled "Diana: Seven days." I think one of the hardest things to come to terms with is the fact that the people that chased her into the tunnel were the same people that were taking photographs of her while she was still dying on the back seat of the car. Anybody who's experienced the loss of a parent at that sort of age would understand that the intensity of grief and loss has a desensitizing effect. That may explain why he was able to lead a kind of party-going lifestyle for many years. And it got him into trouble sometimes. Reporter: Some of those antics landed Harry in the unflattering glare of Britain's tabloids. But princess Diana left an indelible imprint on her boys, as she hoped when she spoke to bbc 1 "Panorama" in 1995. I want them to have an understanding of people's emotions, people's insecurities, people's distress, and people's hopes and dreams. And they have a knowledge. They may never use it but that the seed is there. And I hope it will grow. Because knowledge is power. Reporter: As prince Harry got older he channeled the grief from losing his mother into action. Following royal tradition, Harry joined the army. He became a combat helicopter pilot, serving two tours in Afghanistan. Life in the army for him was very formative and gave him a sense of structure when he needed it, discipline when he knew he needed it. Reporter: It was an experience that changed him. Here he is in 2016 with ABC's robin Roberts. Ten years in the army was the best escape that I've ever had. I felt as though I was really achieving something. I felt as though I was part of a team. All I wanted to do was to prove to other people that I had a certain set of skills, let's say. Flying an apache helicopter, for instance. Rather than just being prince Harry. Reporter: Today prince Harry is a passionate advocate for the armed forces, especially for wounded veterans. We are invictus. Reporter: Through his annual invictus games. No one wants sympathy. All they want is an opportunity to prove themselves. And that's what this is all about. Can I get in the pool? Yes, sir. Come on. Reporter: Despite that sense of purpose, prince Harry watched his older brother, William, marry Kate Middleton and start their family. The three were often together at polo matches and doing charity work. But something was missing. He was always the third wheel on royal engagements. It was the three of them. He didn't have anyone by his side. And that began to matter. I've longed for kids since I was very, very young. So I'm waiting to find the right person, somebody who's willing to take on the job. Reporter: And the woman who is now taking on that role will never meet princess Diana, prince Harry has said mother would most certainly approve. They'd be thick as thieves, without questioning. She would be over the moon, jumping up and down, so excited for me. But then probably best friends, best friends with Meghan. She's with us. I'm sure she's with us, jumping up and down, somewhere else. What do you like about Harry eporter: At Windsor castle the excitement is palpable. The life before the wedding it's turned into a party atmosphere in Windsor. You can see fans lining up, settling in for the because tomorrow is the wedding of their favorite prince. With just hours to go, these fans hoping to catch a glimpse of history. Are you going to be sleeping here tonight? Yes. Maybe not that much sleeping. Reporter: For "Nightline," I'm James Longman in Windsor castle. We'll have full coverage of the royal wedding beginning at 5:00 A.M. Eastern right here on ABC.
This transcript has been automatically generated and may not be 100% accurate.