Reko seems intimidating and assertive, appearing rough around the edges, especially in comparison to her milder female companions such as Nao and Kanna. However, she's generally friendly and has a "big sister" vibe.  She seems to act kinder to those who may be seen as "weak"; this is shown when Reko immediately comforts Kanna when hearing about her sister and treats her more gently. Though, apparently, this was a change to her previous personality before Alice was arrested for murder. Alice also describes Reko as having always been overflowing with talent and charisma from an early age. And that she's a much more put-together person than he is.