#kuroshitsuji chapter 105

"We Grim Reapers were once human too and all. Humans who have committed suicide become 'Grim Reapers' as punishment. We're worked to the bone until the day we're forgiven, a captive audience to the deaths of man. For us, who've committed suicide, to have to bear witness to their earthly regrets and lust for life day in and day out is a depressing state of affairs indeed."

- Sascha Chapter 105

it's so interesting in everyone's case.

Grelle most likely committed due to well, gender dysphoria, which is already upsetting, but it's more upsetting when you realize her being rebirthed as a grim reaper, she still isn't free from that.

William, Ronald, and Undertaker most likely committed due to bullying in general. i have a few theories on it [1 for each character].

William, was most likely bullied or nagged at for his personality, given he's technically that "teachers pet" type of personality, uptight, dignified, aloof, etc. Most likely nihilism as well.

Ronald and Undertaker give me more family issue vibes than anything, Grelle as well. Ronald was most likely consistently nagged at by his family, or others, for being carefree or careless, maybe not even finding meaning in life, a nihilist.

Undertaker, well, to be blunt, he most likely got bullied for being a freak (/hj) as well as a "weird" kid. Thinking about it, his most prominent trait is that he laughs a lot, or wants to laugh. He most likely had an interest in death or what happens after death in his before life, like how he is revealed in Luxury Liner / Book of Atlantic.