Spoiler alert, last warning:

For me it was after finishing the Voodo boys questline and one of my favorite parts in the game, when V just collapsed, Johnny took care of it saving our ass and then gave V his dog tag saying he will go down if the situation ever calls for it.

After saving me, I even told him I would take a bullet for him.

But seeing this scene again in a youtube video made me realize maybe I was a bit naive back then. When V wakes up and the pills are in his hand, I thought the 1st time playing the game "yeah its normal, Johnny took them to bring me to a safe place". The 2nd time watching the video, I thought "wait a minute... maybe he was trying to continue taking them to stay in control forever?".

This is why I love this game...