3rd person pov
Charlie woke up one to be greeted with a letter from Renée. It said that she would have Bella all year and Charlie would have her only in the summer as long as Bella wanted it that way. Charlie couldn't complain because it didn't matter to him, how much time he spent with his daughter, as long as he got to see her.
The first summer that Bella came she would be alone at home when Charlie went anywhere. Though this didn't bother Bella, who found solace in solitude, it bugged Charlie to no extent. He started leaving Bella at Billy's hoping that she would take a liking to Billy's daughters – Rachel and Rebecca, or at least his son Jacob. But Bella had thrown enough tantrums at home to show her dislike of that particular arrangement. By then summer had given way to a new school year and Bella a reason to go back to sunny Phoenix.
One day Charlie overheard Deputy Steve gushing to a bunch of people at the diners about how great and perfect his adopted daughter is, it hit Charlie. He needed a daughter as much as Bella needed a sibling and a friend. He didn't think twice before he rushed into the orphanage. Though the authorities were hesitant since Charlie was a single divorced parent with a child but he pressed his point and they finally gave in. he was lead to the cafeteria were the children were playing. His confidence ebbed out of him and he sat down, overwhelmed by the mass of children there. As he sat he noticed a hunched up figure next to him. She seemed about Bella's age, had her head buried in a book and seemed blissfully unaware of her surroundings. When she realized Charlie's presence she looked up straight to his face, her eyes brimmed with intelligence that was too old for her years. She mumbled a hello and bent back over the book. Charlie smiled to himself thinking about how similar she was to Bella. The same slight frame, dark hair and eyes framed with thick lashes, the ivory pale skin and tentative smile. He introduced himself to her, his mind made up that she would be his daughter from now on. He started to genuinely like her because she was an amazing child who looked to the positive side of everything. So a few visits, phone calls, gifts and months later. The papers were signed, suitcases packed and she was buckled into Charlie's cruiser. He had even told Renée who, skeptical at first but after a few hours worth phone calls to her also, became supportive. They conspired to keep this a secret from Bella.
She settled into her new home perfectly. But she never understood why there were two beds in her room or why there was the artwork of another child's alongside hers. Then one day, a week before summer, she asked Charlie what she would do the whole vacation alone at home while he was out. She silently hoped that she did not have to go to the "rez" because she was already bored of Jacobs irritating talent of throwing mud pies and Rachel and Rebecca's quarrels. But , much to her surprise , he replied by telling her that she had an older sister who lived with Renée , who owned the bed upstairs , who was featured in the photos in the hall. That girl would keep her company. He said "don't worry Izzy Bella you will have Bella." From then on Isabel looked forward to meeting her big sister Isabella.
When Bella stumbled up to her bedroom her nine year old eyes popped open in wonder. She stumbled back into her father staring at the girl sitting in her bedroom. She whirled to face her father who was suppressing a chuckle. "Ummmm…. Dad? Who is this?" she asked and then watched with glee as her face went from bewildered shock to ecstatic joy as he explained that he needed a daughter as much as she needed a sibling. She turned to face Isabel who had stood up. Isabel, though a year and half younger than Bella, was as tall. Bella managed to make it to Izzy's side without tripping, looked into her eyes and said in a chocked up happy voice "I've always wanted a big brother but you'll do. You'll do perfectly!" and hugged her new sister.
They both had a mutual liking to each and were inseparable at most times but could never wrap their heads around the fact that they were family until one day Izzy, as an April fools joke, filled Charlie's gun with sand. Bella knew this, advised her against it but did not stop her because she too wanted to see the look on Charlie's face when he opened the gun to clean it and found it caked with mud. Charlie as routine came home and took his gun to polish bit stopped and said to Bella "honey, could you run down to Mrs. Brown's and get my coat? I have to go out and she was stitching up a loose button." When Bella reached back home with the coat Charlie had a grim expression stuck on his face. He said that Izzy was locked in his room as punishment for the prank that could have cost him his job. Charlie stormed out of the house before Bella could tell him that she was an accomplice.
Bella hunted high and low fir the key but when she couldn't find it she went, neglecting her dinner that Izzy wouldn't get, and sat by the door murmuring comforts to the sobbing Izzy.
When Charlie came home he saw Bella slumped against the wall near his room. Thinking her to be asleep, he opened the door to free Izzy. Bella ducked under his arm and was by her crying sister's side in record time. All three of them realized the depth of Izzy's and Bella's bond when she stood up against her dad for her sister.
She wrapped her arms around Iz, patted her hair as Iz cried into Bella's shoulder and said to Charlie in a threatening voice "don't ever keep me away from my baby sister" and she cooed to Izzy "its okay Izzy. Don't cry" as she wiped her baby sisters tears "Iz and bell are reunited"
Everything after this was all rainbows and sunshine for the two sisters for a couple of summers. Then everything went horribly wrong. And all because of a letter. A meager 50 cent envelope which brought their whole world crashing down.