As Madam Red's ineffectual butler, Grell tends to hang around the edges of the scene, fretting over the socially-unacceptable things that Grell's mistress continually gets up to. When something is not up to Madam Red's exacting standards, she takes it out on Grell whether or not it's actually Grell's fault. Grell's tea is said to be far inferior to Sebastian's.
Meek, easily scandalized, and highly nervous, Grell's personality is entirely at odds with her mistress'. As a result, the other characters tend to either ignore or walk all over Grell.
Grell uses feminine pronouns and has more than a passing interest in Sebastian; at one point Grell compares the two of them to Romeo and Juliet during their battle (leaving Sebastian horrified). Though having an interest in Sebastian, it was stated that her 'true love' is William. Overall, Grell appears to have a tenuous grasp on sanity at best, switching from childish irritation to murderous rage at the drop of a hat.
Like a typical death god, Grell possesses a scythe; however, she had it transformed into a chainsaw because she considered a regular scythe to be old-fashioned. Grell explains that the scythe is capable of cutting through anything; when it cuts through a person, it divides their soul and their memories, thus resulting in that person's memories playing before their eyes.
