The Covenant and the Forerunners

The Sengjuim, the prophets back in the day before they evolved into what they are, were on our side trying to stop the flood. They didn't get punished quite as much because they weren't supplying the troops and everything. So they just kind of got sent back to their homeworld and ticked, taken away. It's odd that they lead the covenant in humanity as their greatest enemy now. That might have made a major difference but it could have been possibly a worser term though.