[quote=@Obscene Symphony]
<Snipped quote by PapiTan>

Followup, how does a Reaper find out they're eligible to become a Reaper? Is that something they're aware of during their life or only when they die? Do people on Earth even know about Reapers?
[/quote]
Reapers will usually be approached by Miss Death directly or someone associated with her and told about their eligibility, so that's something that they'll find out only when they die. 

People on Earth are kind of a mixed bag in terms of knowledge of reapers though. People will rarely witness a reaper or their work, but they usually have no idea what they're seeing when it happens. They do get mistaken for basically grim reapers at times because of the nature of their work though, hence the association to the name reapers.