As a result of the July/August event, Souji will have a completely new AU. In addition, his new AU name will be Souji Seta rather than Souji Narukami.
Souji was born as an unwanted child to a family who simply could not provide to take care of him for unknown reasons. As a result, he was placed into the foster care system shortly after he was born and because of this, Souji has absolutely no recollection of his biological family at all.
For the first few years of his life, he was lucky enough to find a foster home that showed him proper love and support. He grew up like most other children and although he knew that the person raising him wasn't his "real" father, he had no problems with this and was happy with his situation. However, when he became seven, his foster father suddenly passed away and he was then moved between countless foster families and group homes.
While some of these families and homes were good, others weren't so great. Although he didn't have it as bad as some of the horror stories out there, he still faced neglect and emotional/mental abuse. Sometimes, he was the only foster child while other times, he was one of the many in a small home. In all these times though, he had to mainly take care of himself and learn to be completely independent.
Finally, as a stroke of luck, Souji found a woman just before his seventeenth birthday and they struck a bond. Although she was a busy businesswoman who often had long hours at work and left him home alone, she still showed him the love and care that the previous group homes and foster families couldn't provide in the last ten years. Although he was wary about her at first (would she just neglect him like everyone else?), he grew extremely close to her and this was the closest he got to a proper mother figure. Then about a year later, he was properly adopted as her son and Souji finally found a stable living situation in that he was able to live in Recolle and be a "normal" student.
However, due to the difficult past that he had, it came with a lot of negative traits. Firstly, Souji makes a lot of jokes in an attempt to hide his actual feelings and thoughts. He's easy enough to get along with and he never passes a chance to crack a joke but he does it in a way to prevent anyone from actually knowing who he is. It's a self-defence mechanism that he uses in order to push people away as he believes that people will eventually leave him, which is a direct effect from moving from so many different homes and families over a decade.
Although Souji has a tendency to push people away and has an expectation that people will eventually leave him, he also has a fear of being alone. After constantly being taken from home to home, it made him feel like he never truly belonged anywhere and that he will never have true friends. Although he is now in a stable environment after being adopted by his foster mother, he has able fear in the back of his head that tell him that she might change her mind and wouldn't want him anymore. As a result, he still has an issue of distancing himself, even though it only makes his fear of being alone that much more real. It's a self-destructive trait in that he wishes that he could be surrounded with friends but is hesitant on actually letting people in and knowing who he really is. He's fully aware of this problem but has difficulties trying to fix it.
In addition, Souji grew up with the insecurity of wondering why he was not wanted. At times, Souji wondered about his original biological family and even thought about seeking them out before he talked himself out of it. Although he was truly curious to know about his origins, he was always too afraid of the truth. He didn't want to reach out and possibly find out what he was afraid of: that he was truly an unwanted child. This fear of being rejected by his biological parents and any other biological family he might have kept him from ever digging into his own past. However, by never really knowing the truth, he has dug himself into this hole of negative feelings and thoughts that he projects onto himself, only making his feelings of being unwanted that much worse.
Despite all this though, Souji generally shares the same positive traits that his original AU had: being responsible, independent, supportive, and having a sense of humour. He will still act by always cracking a joke or using deadpan humour but with his new AU, there will be new meanings behind this constant jokester persona that Souji portrays.
AU ADDENDUM