REMUS LUPIN
Remus barely remembers his sister, but he will always blame himself for her death. At least until Thorfin Rowle admitted he set them up with Greyback.
James was a best friend. That was why he kept his crush on Lily a secret, why he felt guilty about lying about his lycanthrope, why he never told him he was jealous of Sirius having the label of James' best friend, never voiced that he really wanted to be Harry's godfather, and never got over his death.
Mary's death was the last straw. He could have gotten over Sirius's betrayal and James's death if Mary had been there to help him. He swore never to fall in love again.
When he saw Tonks the first time, she annoyed him as much as Sirius did and he didn't really like her.
Then he started falling for her. He tried to keep it hidden, but Sirius found out somehow and kept trying to set them up. Tonks seemed to find it amusing but Remus just wanted to hex him.
As much as he despised Sirius when they had first met, his death had hurt almost as bad as James's. That was when he realized he wasn't falling for Tonks; he was already in love with her.
Remus had always dreamed of getting married and having a family; he had been jealous of his friends when they had done so. When he proposed to Tonks, he didn't think she'd say yes, he'd done too much to hurt her. Therefore, he was shocked and thrilled as she threw her arms around his neck and practically screamed yes.
Remus didn't know what to think when Tonks told him she was pregnant. He felt guilt, what if it was like him? He or she would be an outcast either way. He was terrified, he didn't know how to be a father, he hardly knew how to be a husband. Most of all, he was happy. He wanted a family, it was dream and it was coming true.
All his doubts about the baby fled when he finally held Teddy. He was so tiny. Teddy clutched his father's thumb tightly and yawned. Who knew babies were so strong? Teddy's hair went from ginger to turquoise. Remus couldn't help but smile. Life was perfect in that moment.
When Kingley's Patronus leapt into his living room, Remus felt cold. As Kingsley's voice announced the battle at Hogwarts, Remus clung to his son, whom he was holding. He knew they needed help, too many Order members had died already. He whispered how much he loved Teddy and gave him a gentle kiss on his forehead before handing him to Dora. Remus knew Dora wouldn't stay no matter how much begging he did, but he hoped still. He tried not to think it might be the last time he saw the people he loved most as he Apparated away.