Should I change any of my character's names? Who?

Christopher
Emily
Matthew
Nathan
Ruby
Violet

What is the setting of your story and what, if any, meaning do these names have for the characters? Having generic names is fine most of the time but it might be interesting to attach more significance to them. For example: Christopher means 'bearing Christ' and was the name of a saint that supposedly carried Jesus across a river. This might play into the characters personality if he is someone that bears the burdens of others when they can no longer stand.

These names don't have any meaning in particular, though they do reflect me and my friends and their names. And if I were to set the story, it would be mostly modern day. Somewhere in northern territory.

So is this non-fiction? If they are based on real people then you should probably ask permission to use their real names. Especially if you are going to be telling a true story.

No this isn't non-fiction. Those aren't their real names either. What I'm writing isn't based of of my experiences, it's just something I've conceived myself.

I don't think you need to change anything if those are the names you like. If you're worried they're too common though, maybe give them nicknames, or give them really interesting last names. Emily could go by "Em," or "Millie" for example, and Christopher's last name could be Acker or Byrant. Just some ideas :)