In episode 9 and episode 10 of Re:Zero, when Rem uses
her horn to engage beasts, it seems that she cannot control herself.
In episode 10, she also
attacks Subaru and Ram. Subaru has to hit her horn to bring her out of the madness.
Episode 10 at 19:47
However, in episode 11 on the flashback when Ram and Rem were young,
none of them become crazy when they use their horns.
Episode 11 at 1:26
Episode 11 at 2:17
Could anyone explain it to me?
Is madness the side-effect of using the horn, or are there any other causes? Because as I see, it happened to Rem in the forest with mabeast (demon beast) only.