I have three mcs that have first names that begin with the same letter. I have Tom, Terrence and Todd. Now, Todd's full name is Todd "Spider" Wills and he is refered to as Spider most everywhere else in the book. But Tom and Terrence are used whenever their names are mentioned.
Question: If Todd is usually called "Spider" then when is he called "Todd?" At my job and with friends and family, people know me by my nickname, not the name on my birth certificate. So why would Todd be called both Todd and Spider in your novel?
Then again, I read a book where half the random 'walk-on walk-off' characters were called Jean-something or other. Jean-Claire, Jean-Paul, Jean-Etriffe. It was part of the world-building and it was quite interesting for that, added to the atmosphere.
I really do not like when very minor characters have names. Giving a character a name makes me think that person is important to the story in some way. If it's just the waiter you only see once, or the dentist's receptionist that only appears once, or someone else that is very incidental to the story line, don't name him!
Harry, Hermione, Hagrid, Hedwig, Hogwarts...
Yeah, but that's a boy, a girl, a (what exactly is Hagrid, anyway? just a big guy?), an owl, a place ... So it's not the first letter, but the identifiers to the name that make it easy to remember.
Later in the book, when things are finally happening where their different identities are actually important, I'm having to flip back and figure out who is who. A glossary of names would actually have been helpful.
... so I wonder if the lack is something in me. As far as I know, I'm not dyslexic or anything, but names have always been hard for me.
I get names mixed up too, especially with a large number of characters. Even in series that I've read for years, I'll have to think back to how they're connected to each other. It's just a blank spot in my memory bank.
Some novels used to have a list of character names, but it's uncommon. I rather liked that feature. At times I've thought about writing my own list when I start a new novel. Maybe just an index card I can tuck into the pages.
The problems I usually have, as a reader, stem from names that are unusual, and hard to pronounce. For instance, Laoghaire is a name in a novel I've read (Outlander). It's the name of a town in Ireland I've been to, so I know it's pronounced Leery, but most people won't know that. If there were another character in the novel named Lenihahon, for instance, I would confuse the two - unusual names, hard to pronounce, both start with L - they would conflate in my mind.
Oh yeah! In my teens I was most taken with British novels, and there are a lot of names I pronounced incorrectly. This was way before the Internet made all things knowable. I mangled my way through a lot of stories. Some of those old English names, like Cholmondley, which is pronounced "Chumley" I think. Yep - just checked - there's even a YouTube video on how to pronounce it. (is there a YouTube video on everything?)
people call me by my siblings names all the time.
My brother and husband have names that aren't really similar but are both one syllable and start with the G (like giraffe) sound. Separate, no problem. When we're all together, I'm always mixing them up.
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For the OP - I'm with the group that says make it easy on your reader, and don't use both Tom and Todd. Terence is fine - different look to the name and longer.