The Quandaries and Possibilities of Mass Effect 3

The folks at Shadowlocked have penned a lengthy piece that examines many of the characters we met and decisions we made during Mass Effect and Mass Effect 2, and where these events could take us during Mass Effect 3.
The Quarians also have a big decision ahead of them: should they try to retake their home planet by battling the Geth, or continue to live as nomadic separatists, roaming from one side of the galaxy to the other? In ME2, you have the chance to influence this particular decision, and although the ramifications of your advice are not clear, it's a safe bet that somewhere down the line the consequences of this idle chat will make themselves known. The Geth themselves, meanwhile, are having a civil war of their own between the (heretics) (the Geth who worked with Sovereign and Saren) and the (true Geth). By assisting Legion in ME2, Shepard has the option of either destroying the Heretics or rewriting their programming, potentially making them an ally. Either option is clearly going to have strong repercussions for the Geth, and may affect the Quarians' chances with regards to retaking their homeworld.

Finally, there's us - humanity. At the end of both ME1 and ME2, Shepard is given an opportunity to greatly alter humanity's destiny. If you elected the Renegade action, you let the Citadel Council die, replacing them with a barely-disguised human dictatorship. If your conscience got the better of you, however, you could save the Council at the cost of many human lives, but secure a seat for humanity on the Council itself. Rather irritatingly, despite saving their lives, the Council continue to be nothing but a thorn in your side throughout the short time you see them in ME2, offering virtually no aid.

Surely in ME3, with the Reapers now attacking Earth outright, Shepard can count upon the Council's aid? You'd think so, but politics is ever the field of self-interest and it's not too difficult to imagine the Council being as short-sighted as they have been for the last two games. That leaves Cerberus and the Illusive Man, who we can almost certainly say will do whatever it takes to secure humanity's future, regardless of the cost.