I've read that characters with low-canon appearance is case-by-case and I want to be more certain before considering apping so:

What about characters that do not actually appear in the canon, either because they were a murder victim or something. However, this character was one of the main character's best friends and such so he's spoken about quite a bit/there is one flashback with him in it so there is information on his background and personality. We just never get to actually see it. Would a case like this be appable at all?