If I do something to help you it builds loyalty to me.

Other sorts of loyalty are not so honest such as people who are loyal to those who feed them or else they might die. Most of general society thinks like this. They won't smash the system which oppresses them because it also feeds them.

They know of no other way and have not been able to conceive the idea of a better one so they stay loyal out of survival instinct.

You help me and I help you creates loyalty which is strong and lasting.

Deceivers can make you loyal to them by giving you a little and getting a lot from you but making you think the deal was worth it. Repeated over and over they actually own you and can ask you to do things for them you would not normally do.