Headcannon: there are two ways for changelings to evolve; the first is by the tradition ways of evolution which take a long time. But there is a faster second method to having a changeling evolve, this would involve a certain creature inside certain changeling hives called the brood lord. The brood lord is a rare creature as it can only be created by one medical drone going through a set of trials when its chosen by an ancient voice within the hive mind (to be continued)