Prototype

To consume a character, approach them, grab them with CIRCLE, and then press TRIANGLE to consume them. Consuming characters will give you health (and you will consume for health often), and can also give you memories and abilities if prompted by the story or if the person you consume is a Web of Intrigue target. You should have this unlocked by the time you finished your first playthrough of the story mode, but if you don't get it by the end of the story, there are plenty of people to consume in Free Roam, so just walk the streets and eat everyone until you unlock the trophy.

You can track you progress under the Statistics -> Consumes page on the pause menu.