The A Road Less Traveled trophy in Borderlands 2 is story-related and can't be missed.
You will unlock the trophy once you complete the steps below (taken from the Xbox 360 guide on TA by mast3r 0r0m1s):
*** Spoiler - click to reveal ***- Go to Sanctuary
- Use Catch-A-Ride
- Get the Hyperion Adapter and install it
- Get vehicle and jump gap
- Find Corporal Reiss and his attackers (after going to Sanctuary)
- Get Power Core (Bonus for killing 20 Bloodshots)
- Contact Lt. Davis (Back at Sanctuary)
- Deliver/Remove/Install (in that order) Power Core