4. "Tommy" Is Ellie's Brother?
The latter portions of the game describe a cutscene "Reunited With Tommy", a character who isn't mentioned in any previous cut-scenes. This suggests that he is probably a figure from either Ellie or Joel's pasts, and given that Joel is the hardened, near-sociopathic veteran whereas Ellie is the more emotional, social one, we're going to go with it being someone that she knows. In fact, I'm going to go out on a limb - I think that Tommy is going to be her brother. Let's face it, her parents probably won't have survived long in a zombie apocalypse, but a young man? Absolutely. Other cut-scenes in this section include "Ellie Is Gone" and "Ellie Reunite", suggesting she either runs off or gets attacked or something, and I'm betting that Tommy, in trying to save her, gets killed, hence the final cut-scene, "Bye Tommy".