Originally Posted by Lana

Vito's "to be respected and honored by those whom he helped” - always with a caveat
Quote
Some day and that day may never come, I'll call upon you to do a service for me - Keeps hanging over their head

When Tom called upon Bonasera to do his service for Vito

in the novel:
Amerigo Bonasera felt the coffee churning sourly in his stomach, felt himself going a little sick.
It was more than a year since he had put himself in the debt of the Don to avenge his daughter’s honor and in that time the knowledge that he must pay that debt had receded.

Now Bonasera felt the sickness of a man faced with disaster. He waited with a feeling of the utmost despair.