Throughout the game you will be presented with choices during a cut-scene to do something with evil Karma or good Karma. This is the second choice you will have to make. Choose the
Good Karma (blue) option and complete the blue Star mission
Trash the Stash to get this trophy.
If you want to know what the choice is, hit the spoiler below:
*** Spoiler - click to reveal ***After chasing Fetch into the theater and getting her power, you will you will have to convince your brother to not take Fetch in to lock her up. You will then have the Karma options to Redeem Fetch, or Corrupt Fetch. Either way your brother will let Fetch go, but if you choose Redeem Fetch then you will will start you down the path where Fetch will no longer kill. The Blue Star mission Trash the Stash is available once the cut scene is over. To beat the mission easily, follow Fetch and the mission markers and knock out all the Drug Dealers with your new powers. After a few locations the mission will be complete and the trophy will pop.