Has this ever happened to you while writing your novel?
One of your characters starts off as a nasty young man, but somewhere in the middle of the story, he slowly changes into an indifferent one when he should still be nasty. I call this character drift. It happens a lot for a variety of reasons and it’s real problem, especially, the nasty character has to be nasty at the climax. If this character is no longer nasty, the climax has the potential to fail.
I created a character spreadsheet to help prevent this drift. The more characters the story has, the more valuable this aid is. The spreadsheet is much larger than what is shown in the graphic below.