Mine is James Holden and the crew of the Rocinante. For those who don’t know these are the protagonists in The Expanse a series of nine books and a few novellas.
Partly this is due to the sheer amount of time I spent reading the series; hundreds of hours over months created an attachment. Secondly the characters growth through the series was unlike any other book I’ve read. The series was simply excellent from beginning to end.
Maybe I’m overly sentimental but finishing the series felt like losing a friend.