Your grandfather inherited his house and its secret room

You find a photo of your grandfather when he was young,and a friend whose name is written on it is Xenos

When you open the chest,you are surprised,it's Xenos and what's more strange is that he is still young

There is a statement that says"My granddaughter,this is a gift from grandfather,you must inject the medicine to revive Xenos"

There is indeed an injection containing medicine,is your grandfather a psychopath?