User blog comment:LilyheartsLightning/Citadel and Reckoning DLC announced/@comment-3228423-20130225230558/@comment-4937645-20130226063359

Collectors is kind of a weird choice, honestly, unless somehow it gets explained in the SP DLC or some other way.

Collectors were bad guys, always have been. Anyone who played ME2 outta know that - they are corrupted, completely reaper-controlled former Protehans. So and unlike the ex-Cerberus and Geth classes, there's no in-game or in-universe explanation for why suddenly a collector would somehow turn good.

My personal hope? This is indicative of where the Citadel DLC is going. How cool would it be to go through the Omega-4 Relay again? It seems doable, especially since in Omega we already retook the system...and it could provide an explanation (maybe) for why suddenly collectors are "awakening" and helping the N7 battles. Probably way too much to hope for, but hey....