Seems the type you become is either through repressed desires or similar thought patterns.
Already confirmed during the first few updates. What Abyssal the Fleet Girl becomes is based on the trauma that Abyssalized them in the first place. From what I can guess, Taihou/Anchorage Water Oni's was betrayal, Yukikaze/Seaport's was survivor's guilt, Ryujou/Isolated Island's was being a flattop. Don't know about Midway, but I guess Mama Houshou/Airfield might have snapped due to having to deal with a shitty Admiral for too long.
She may be like historic Houshou that survive ww2 : most of her daughter(or younger sisters or students) die and she survive because she is too weak for frontline then comsume by thought like "only if i am stronger and can fought togethet with them they may survive" or somethomg like that then she became abyssal and get strength she want after that she won`t let anyone hurt her (abyssal) daughters(or younger sisters or students) without walk over her dead body Story like that may be good for Sensei(or mother)Houshou
