I dont think the hero is a bad person as like his Sister said its probably like she got jealous her and killled and in this timeline they probably be something like friends or he will go back his own world with the help of fl I dont even think him as a second lead or anything
Also consider this: the sister has NO reason to lie about who was involved in the whole scheme. FL was moments from death; and sometimes the truth is more worthy to tell than lies. Also yeah JiHo is the worst.
I dont think the hero is a bad person as like his Sister said its probably like she got jealous her and killled and in this timeline they probably be something like friends or he will go back his own world with the help of fl I dont even think him as a second lead or anything