Kingdom Hearts vs Honkai: Sar Rail
Connection:
Both are blue haired sword fighters from beloved games who lived normal lives in their home worlds (Radiant Garden and Xianzhou Cangcheng respectively) until they were swallowed up by a hostile force invasion (Heartless and Denizens of Abundance respectively)
Both would eventually become close friends to comrades (Axel and Jing Yuan respectively) however tragedy would fall upon them after losing a female friend close to them (Subject X and Baiheng respectively). This event ultimately lead them down a dark path that lead then to being not human (Isa became a Nobody while Jingliu became Mara-Struck)
Both would go onto be driven to insanity and would be a force to be reckoned with. Both also have had made a deal with major blonde hair men (Ansem the Wise and Luocha respectively) and being/have been a part of major organizations (Organizations XIII and Xianzhou Alliance respectively)
Both have also severed ties with their friends for many reasons (Axel went on to make other friends betraying Saix's friendship as well as betraying as well as Organization XIII, while Jing Yuan saw Jingliu was a Mara-Struck killing people on sight and needed to be taken down), and which leads to conflict with them before ultimately being defeated by them
Eventually both managed to reclaim their sanity and humanity in someway (Isa was restored in his human body and Jingliu wears a blindfold to prevent Mara from taking over) and would go on to redeem themselves for their actions
