Don't know if this helps but their will always be a dominate member of the pair and as they set the pecking order one will stay put but while the other sits outside, I noticed this this when I put a pair in QT, they fought for a while and then as it settled down one would stay in the pvc pipe while the other would stay outside next to it while they slept, I also noticed the same when at the LFS, one would stay on the anemone while the other would hover around it. Welcome to R2R!!!