Rem's dangerousness stems from her full participation in Misa's choices. Rem even goes so far as to defend and guard Misa to the end. Having a Shinigami on your side makes you a more powerful character, as we'll see next. 6 Amane Misa
The Relight movies are a shortened version of the anime series. The movie' idea is that Ryuk narrates the narrative to another Shinigami. Due to his time spent in the Human World with Light, Ryuk becomes famous with other Shinigami following Light's death and his return to the Shinigami Realm. Ryuk's narrative eventually draws the notice of an unknown Shinigami, who pays a visit to Ryuk to hear it.
RELATED: 5 Times Death Note When Yagami Lights Up Wasn't it THAT bad? Light needed to persuade L that he and Misa were innocent, and in order to do so, Light handed himself in and surrendered his Death Note memories. Simultaneously, Rem brought his notebook under Light's direction and found a new owner: the avaricious Kyosuke Higuchi. Rem became Higuchi's official shinigami companion and remained with him until Light murdered him in order for him to recover his abilities and memories. During the period when Light and Misa had no memories or notebooks, they assisted L in her investigation of Higuchi, and Rem even asked Misa to assist her in identifying Higuchi as Kira. Then, once Higuchi was apprehended and executed, Rem became a free agent, which numerous members of the Kira investigative team, including L, saw.
Rem delivers his Death Note to Misa after Shinigami Gelus sacrifices his life to save the human Misa Amane. Rem starts caring for Misa and tries to keep her out of harm's path from then on. Rem becomes aware of Light's intention to use Misa as an instrument after meeting Light Yagami. Rem declares to Light that if his plans do any harm to Misa, she will execute him. This ultimately leads to Rem's death, as Light learns out how to manipulate Rem into killing L for him by demonstrating a scenario in which mischief would befall Misa in general. Overall, she bites the dust when she comes up with L's name. Written by monica thiongo for Zerochan.
