Wasn't sure if/how I wanted to do this quest, but all I did was tell the courser I was willing to accept his help in attaining the synth.

Piper even backed me up, saying we could use the extra help. I accepted, then Piper disliked it. Can anyone explain this to me?

Piper directed you to the Railroad.

She kind of has sympathies.

Thank you, I wasn't entirely sure. I'm helping the Railroad, so I'll stick with them, also because I really like Piper. Helped all synths so far.
It's hard to leave quests open, though Thanks!

The Railroad was my least favorite faction when I first got the game.

Then I met them.

What a WONDERFULLY weird group of people.

They're my favorite faction. Did Piper give me the Freedom Road quest? I don't remember

I got that by just overhearing some guys talking in DC. They were standing outside the detective's office.

I got the quest over-hearing people in Diamond City mention "Follow the Freedom Trail", and then much later Piper brought it up.

She mentions it, yeah.