ALLEN PARK, Mich. -- Alex Carter opened his front door on one of the worst days of his life. The girl he asked to come over after his sister's death -- the girl he never met before but knew from Twitter and text messages -- stood there as he opened it.

He didn't know it at the time, but opening that door on Feb. 21, 2012 would lead to the second drastic change that day in Carter's life. He was 17 at the time.

Carter, who is entering his first training camp with the Detroit Lions after being their third-round pick in May, remembers the day his sister, Cameron, died unexpectedly of Type 1 diabetes at age 14. He heard his mom, Renee, scream early that morning. He thought she found a spider. Then Alex went to Cameron's room and saw her lying on the floor. He thought Cameron passed out and went to pick up his other sister at school before driving to the hospital.

It was there he found out his sister had died.

"I kind of broke down. Ran away," Alex said. "It was pretty tough. Just out the door. I couldn't believe it. Down the street, started crying. Then I got myself back together and came in.

"My parents were like you have two young sisters still, you've got to be a man and you've got to show them you can keep them together still."

As he tried to keep himself from falling apart, he texted a girl he had been communicating with for months but had never met. He asked her to come over. This is how Ariana Alston ended up at the Carter home holding Chipotle and "Dance, Dance, Revolution" for the Wii.

They hugged. Ariana walked in and met Alex's grieving family and friends. Ariana, who now goes by Ariana Carter, showed up that day and has stayed by Alex's side ever since.

"Never thought she was going to be my wife," Alex said. "It's just another friend, you know. Everyone's sad. My sister passed away. So that's what it was at first. She came in and kind of lifted the mood. She was making some jokes, made everyone feel happy."

Ariana helped Alex as he struggled with Cameron's death. He considered not going to Stanford because of the distance. Renee convinced him Cameron would still want him to go. Since Cameron's death, Alex has tried to raise awareness for diabetes and is planning to do even more to fight the disease in the future.

Alex and Ariana followed each other on Twitter in 2011 -- and still joke about who followed who first. They direct messaged and texted daily for weeks. Three potential meetings were canceled for various reasons -- the last so Alex could attend one of his sisters' volleyball matches on Feb. 20, 2012.

When Ariana had not heard from Alex on Feb. 21, she scanned Twitter and saw messages and hashtags offering prayers for the Carters.

Not going to the same high school as Alex in Ashburn, Virginia -- he went to Briar Woods and she went to Stone Bridge -- she didn't know what was going on.

Eventually she found out. She texted Alex and told him to let her know if he needed anything.

Alex told her to come over.

"I'm like, 'If this is going to help you, me showing up, I'm going to do whatever I can to be there for you,'" Ariana said. "'I'll come over.'"

One day turned into two weeks and a new routine. After soccer practice, Ariana went to Alex's house with movies and video games. A legitimate friendship formed. Alex eventually asked Ariana to prom as friends. She asked him to hers as well.

"After that I was like, all right, this girl is very beautiful," Alex said. "I could see myself with her."

Long-distance dating was the option with Alex at Stanford as a freshman cornerback and Ariana still in high school and then attended college at Florida Atlantic and VCU. With 2,800 miles separating them, they decided to try to make it work.

The relationship survived with phone calls, text messages, Skype and FaceTime and helped Alex refine his communication skills both with Ariana and in public.

By his junior year at Stanford, Alex knew he wanted to marry Ariana and proposed during Christmas break by traveling back to Virginia from school a day early. He initially planned on proposing in Georgetown, but even the proposal had a detour.

Ariana wouldn't go to Georgetown with her friends because of the weather, so Alex worked with Ariana's sister, Tatiana, to change the proposal to the basement of her house. Ariana walked downstairs, saw pictures of herself and Alex flashing on a screen and a large box that was supposed to be in Georgetown.

Instead of hiding in the box, he was waiting in a room behind it. When she flipped the box over, he stepped out, dropped to one knee and proposed. Not exactly how he planned it, but Ariana said it was perfect for the two of them.

He declared for the draft less than a month later and the pair were married on July 11 in Lake Tahoe.

"In our hearts we knew, like I'm ready for this," Ariana said. "And we had already talked about it at the beginning of the relationship. We were those kids that were like, 'Hey, we're going to get married one day.' I was 16 [when we met]. I was so excited.

"We kind of knew at the beginning, like, 'Hi, I think that you're the one for me.' He was like, ‘All right, that's cool. I think you're the one for me, too.' "