Capelli was a part of Nathan Hale's squad of Sentinels (an elite group of operatives who survived the Chimeran infection and become stronger through it) during Resistance 2. He was the heavy weapons expert of the team, always equipped with a HVAP Wraith Gatling Gun. Capelli would constantly be at odds with Nathan Hale throughout Resistance 2, disagreeing with his methods, thinking Nathan was far too reckless and shown little regard for keeping his 'condition' in check. Capelli was eventually proven correct: Hale's insistance on doing all the important missions himself instead of getting the medicine he needed to contain the virus ultimately lead to Hale's mind being taken over by the Chimera, and Capelli was reluctantly forced to mercy-kill his friend to prevent him from transforming completely.
As one of the only surviving characters from Resistance 2, Capelli has become the series new leading man, and the main protagonist for Resistance 3. He, along with Dr. Fyodor Malikov (and John Harper in co-op mode), must go to New York City to destroy a Cryogenic tower in an attempt to delay the Chimera's total extermination of the Human race.