I love Dom and Letty so this is how i think their relationship should have developed.
Across the street from the Toretto house a moving truck was parked in front of the house that stood there. A little girl stood in front of it watching the movers move all the things from inside the truck to inside the house. Another little girl ran from inside the Toretto house. She ran to the little girl standing in front of the truck she said, "Hi my names Mia Toretto I live across the street. And I'm five! What's your name?" The other little girl looked at Mia curiously, but slowly smiled and said, "Hi Mia I'm Leticia Ortiz, but I go by Letty because it's easier to say and spell and I'm five too." They both giggled at that. Mia then said, "We should be best friends!" Letty looked thoughtful then said very seriously, "Mia I'd love to be your best friend!" Mia squealed and pulled Letty into a tight hug and Letty hugged her back. The girls continued to talk to each other about trivial things like little girls do when they heard yelling, "Mia!? Mia where are you?!" Mia turned towards her house and screamed, "Dom! I'm talking to my new best friend so pipe down!" Letty giggled as Dom came storming towards them with another boy in tow. He said, "Mia one you can't go outside by yourself. You know that! And two you definitely can't cross the street by yourself! I know you know that!" she looked a little guilty as she said, "I'm sorry Dommy I just want to meet the new people." Dom sighed and said, "Just don't do it again. Okay?" She nodded with a little pout. Letty giggled and Mia's pout turned to a smile as she said, "Dom this is my new bestest friend Letty! Letty this is my big brother Dom and his best friend Vince." Letty giggled and said, "Hello." Dom nodded and said, "Hello Letty." Mia asked, "Do you want to go play with dolls at my house? It's ok right Dom?" Letty grimaced a little and said, "I'd rather play with cars."
Dom and Vince were shocked girls liked dolls and boys like cars. This little girl was definitely not a normal girl. They were impressed. And Dom said, "Sur its okay if you come over Letty. You're always welcome." Mia sighed, but said, "How about I play with my dolls and you play with your cars?" Letty nodded excitedly and said, "Let me ask my mom!" She took Mia's hand and ran towards the house with Mia in tow. As they were about to go in a woman came out and Letty looked up at her with big puppy dog eyes and said, "Mama this is Mia she lives across the street can I go play at her house?" Letty's mom nod and said, "Yeah sure, whatever. Be home later on I guess." Letty nodded and said, "Of course mama." Letty grabbed her car from the porch and hooked arms with Mia Vince took Mia's hand and Dom took Letty's as they walked them across the street. A car pulled into the Toretto's drive way out stepped Tony Toretto. Mia dragged Letty over to him and said, "Daddy this is Letty. Letty this is my daddy. Letty just moved over there." She points across the street. Tony bent down and said, "Hello Letty." Letty smiles and said, "Hi Mr. Toretto." Tony shakes his head and says, "Please Letty call me Tony." Letty giggles and said, "Ok Tony!" Tony patted her head and said, "Vince Your mom wants you home. And Dom take Letty inside I need to talk to your sister."
Vince walked off since he only lived down the road and Dom took Letty's hand and took her inside. Once they were inside Letty sat on the floor and happily played with her car eleven year old Dominic just sat there and watched her. Finally he asked, "Do you even know what kind of car that is?" Letty giggles and says, "Of course I do. It's a 1968 Dodge charger. I love cars I want to be able to work on them some day like my daddy did before he went away." Dom looks at her curiously impressed that she knew the car was even more impressed that she was fascinated by cars, but curious as to where her dad was. So he asked, "Where'd your dad go?" She looks up at him with her big eyes and says, "He left said he didn't love mommy anymore and said he loved me, but he just wasn't ready for me. It's ok though he taught me about cars before he left. He told me as long as I had cars in my life I'd always have a piece of him." Dom looked at this little girl in amazement he decided there and then him and Vince had to protect her and watch out for her like they did Mia. He'd take her under his wing and teach her more about cars, till she knows everything he does. With the help of Tony of course.
Just then Mia ran through the door and said, "Letty let's go play in my room!" Letty nodded and gave Dom a hug catching him off guard, but he hugged her back anyway. She let go and followed Mia up the stairs. Dom looked at his father and said, "Dad we have to help watch out for her. She seems like a good kid in a bad life." Tony asks, "What do you mean bad life?" Dom said, "Well she asked her mom if she could come over here and her mom literally said, 'Yeah, Sure whatever. Be home later on I guess.' Then walked away didn't meet me or ask how old I was or ask if you were home nothing. Then she just told me her dad left because he didn't love her mommy anymore and that he just wasn't ready for her. She said he taught her about cars before he left and said as long as she always loved cars she'd always have a piece of him. She told the exact car her toy car was the make model and year. I think we should keep teaching her about cars." Tony was in shocked and felt lots of sympathy for this poor little girl. He was proud of his son to want to watch out for her and he knew it's what they needed to do and what they would do. He said, "Your right son. We will teach her about cars and we will watch out for her no matter what." Tony patted his sons back then walked into the kitchen to start dinner. He asked his son to watch the food while he walked across the street to talk to Letty's mother.
When he got to Letty's he knocked on the door a young women came out and said, "Yeah?" Tony was a little surprised by this, but said nothing about her rudeness as he said, "Hello I'm Tony I live across the street you daughter is over there playing with my daughter and I was wondering if it was ok for her to stay for dinner." The women rolled her eyes and said, "Yeah. That's fine. She has school in the morning or something remind her not to wake me and to not miss the bus or she can walk." Tony was shocked he knew it might be bad, but not this bad. He said, "Well her and Mia go to the same school I can bring her if you want." The women looked him in the eyes and said, "I honestly don't care you want to deal with the brat then deal with her." She then turned around and went inside. Tony wondered how Letty was such a happy child with the life she had, but he'd never question it. She was a special little girl and he would treat like his own. He'd make up for her mom and dad. And if it ever came to it he'd take her in and protect her like his own as well. When he got home Vince was back and he and Dom were watching TV he went and checked to food and it was done and cooling. He told the boys to go set the table and went to get the girls. He told the girls dinner was ready Letty said, "Does that mean I need to go home?" Tony shook his head and said, "No sweetie I asked your mother she said it was ok." Letty nodded excitedly and they made their way down the stairs. They all sat around the table and Vince was the first to grab at the food so Dom said, "Ha! Vince say grace." And he did as Letty looked around she was excited to know her best friend came with an amazing family.