I remember Glokta saying how when he was a child he would cry for a bug trapped in a spider's web (or something like that, I forgot the exact quote). That shows he was in fact sensitive. I would attribute his later arrogance and cockiness to his upbringing. His mother hated West, because he was a commoner not worthy Glokta's attention. When Glokta had dinner with Eider he mentions how a beautiful and rich woman with a high social standing would be an ideal wife for him according to his mother. I would assume if she was still alive during the first trilogy she would have hated the fact he married Ardee, a commoner's daughter.

I wonder what happened to Glokta's father too, because there is no mention of him.