Pete Theory
****WARNING: MAJOR STRAWMAN BELOW. 90% LIKELY TO BE BULLTURD.****
My rambling theory on why Pete may be the "..you were dead" character.
Save Nick: If you save Nick, he'll fire several rounds towards the zombies. Killing them. You then see Pete slumped against the rock, but there's a noticeable lack of gore. This could just be Telltale not wasting assets on it, but Pete is looking AWAY from the camera. We hear him cry out, but we never really see the zombies landing any actual bites on him; the camera focuses on Nick the entire time he's shooting.
Also note that unless Nick accidentally hit Pete with one of his rounds (entirely possible), why would a few bites manage to outright kill him? Unless he went straight into shock.
Save Pete: If you go with Pete the preview shows him preparing to amputate his leg/ankle/whatever. In this case, it's possible Clem could leave Pete if the attempt fails, or he could tell her to leave him.
Reasons Against: We see the zombies grab ahold of Pete, even if we don't (on-screen) see them bite at him. That, and... y'know, being slumped up against a boulder, not moving, and not calling out.
The other group members don't see to recognise the members of the other group with the firearms. That being said, there could be a reveal right before to the adult members that it is Pete, with Clem admitting she thought he was dead.
Personal Thoughts: Telltale have pulled the red herring before with the Nick/Kenny hat model. It wouldn't shock me at all if they're trying to set up the implication that it's going to be a S1 member, when in fact is related just to the Season 2 characters so it's even more of a surprise.
Keep in mind even I don't belive my own theory is solid at all. This was just one theory I had.