Prodigal reappearing at the end of Hero Project.
That was the only part I didn't remember from my first playthrough, but after deciding to go through "The Prodigy" again, I remembered how much I LOVED Prodigal as a character, and I kept hoping she'd show up in Herofall, if only for a cameo.
Then after watching Lucky go into a coma, breaking up with Black Magic, and losing my powers, I was pretty darn sad at my ending, even thinking about going again just to see if I could change things.
Then I read a line I'd remember for the rest of the trilogy.
"Are we really all that tired, Chicken?"
I literately yelled in excitement when I read that, clicked Next, and shouted "PRODIGAL IS BACK, BABY!" and kept reading.
Then she gave me the news that her mom was alive, and I was hooked.
So yeah, that's my favorite moment, probably the happiest I was to see Prodigal, and it kinda makes me feel better after watching her die.