One half of the Evil Twins, Moritz is more goofy and sillier than his twin brother, and can be pretty simple and airheaded, either blurting out things he shouldn't or complaining about being hungry (to Victor's annoyance). Despite this, he has a similar urge for revenge like his brother and carries the same amount of resentment, only dishing it out a different way.
Moritz's voice is higher pitched than Victor's, here is a reference: https://youtu.be/1ub7jgtWfiI?t=396
Try going for that accent and tone.