Sucked into another world from Earth? Check.

Magic, mayhem and a fight for survival? Check.

Not sure who's gonna survive or get killed off at a moment's notice? Check check check.

This line of books contains the stories for many of the prominent characters or guildmates (prior to meeting Trey) surrounding Trey's character in the book: Eleknar's Heir, The Infernal Prince (which is still currently ongoing)

Reading these books before the main book can be done without ruining anything (though the character you're invested in may disappear from this book into the main storyline after a couple dozen chapters), but that's up to you ^.^