nona (the locked tomb) - i think she'd be DELIGHTFUL to write but getting existing characters' voices down is the nightmare realm for me. thankfully she only has one book of existing as a person in canon so. hmm. actually this one's not impossible
thistle (dungeon meshi) - the boy of a thousand Yikes. he did so much wrong & i should write more guys. has that beloved mix of 'deranged but really good at what he does'
shen jiu or shang qinghua from the scum villain's self-saving system. again i gotta add more boys to my repertoire. probably not sy/sqq tho, he's outside my range
if i had infinite brainpower i'd play one of the witches from umineko but Man i am not good enough of a writer for that. i can only appreciate from afar