# Confusion on co-moving distance and the Big Bang

I'm at sea. From the wiki. entry https://en.wikipedia.org/wiki/Comoving_and_proper_distances : “..Most textbooks and research papers define the comoving distance between comoving observers to be a fixed unchanging quantity independent of time, while calling the dynamic, changing distance between them "proper distance”..” My confusion: Two galaxies having a comoving distance of, say, 1/2 billion LY, according to the entry, have this as a fixed distance for ALL time. But how do I reconcile that there was a time when their comoving distance could easily have been 1/100th or 1/1000th that distance, closer to the Big Bang?