The realization hits Qui-gon out of the blue. One minute he's describing the intricacies of the Scillian political hierarchy, turning to his apprentice to make sure he registers the importance of the tertiary senatorial aide in regards to foreign policy, and he knows.

Obi-wan is not, and never will be, Xanatos DuCrion.

And as surely as he knows this, as happy as he is that this is true and his padawan will never turn from the light, will never willingly betray him, he knows with a similar gut-wrenching certainty that he has hurt this boy, time and again, with the callous conviction that he would.