By definition in literature, a "motif" is a recurring element with symbolic significance. It can contribute to the theme of a story or invoke certain emotions.
As funny it sounds, Alexander Gordon managed to turn a particularly funny quirk into a motif in "Chronicles of Eden." That being snoring.
In most stories, snoring usually invokes humor. In this case, Daniel's snoring being so loud it could rattle a forest or cause an avalanche. Additionally, it serves as a telltale sign of genuine romance. By loving Daniel, the girls are able to sleep perfectly fine next to him despite the volume.
A cool and humorous motif, but nothing really eye catching . . . at first. . . .
In Act IX, we learned that Lelu was the only centaur in all Ruhelia who snored. Nobody could find a cause for it and Lelu thought it only contributed to her being broken.
Additionally, in Act XI, Vale was shocked to discover that Lelu, a centaur, was able to snore. According to Vale, monsters shouldn't be capable of snoring and she actually seemed worried by it. She said "the others" would want to know about it — whoever THEY are. . . .
This peculiarity would also explain why no monsters understand what snoring is. Alyssa and Squeak both thought Daniel was suffering when they first heard him do his nightly quirk, same as Star, Cindy, and Snapper.
What is it about snoring that's so significant in these stories? Why is Lelu able to do it? Why is it so unheard of from monsters? Any ideas?