similar in origin to how lee’s narration tends to spiral into rhyme schemes when his mind is foggy and getting lost in future (or past) memories, i think angels are metaphysically incapable of vocally/orally lying in rhyme or iambic pentameter.
I won’t over explain why because i think there’s delight and awe in hinting at otherworldly systems without fully laying it out (kind of like how magic tricks lose their charm if you show them how it’s done) but i will remind you that angels, in their true forms, are infallible and inseparable from the underpinning physics and laws of this world.
rhyming and rhyme schemes are a human(-y) invention but an unintentional discovery and application of higher dimensional frequencies. rhymes and rhyme schemes vibrate in a tempo that dimly pierces our mortal dimensional veil. like the faintest glow. and because of that higher dimensional fluency, it interacts with angels in a unique way (like how magenta is a reductive absence and effects angels). an angel attempting to say a lie that rhymes or is in a rhyme scheme is rudimentarily equivalent to a human being trying to flawlessly say a tongue twister (rhymes/rhythm) in glass-breaking-high soprano (lies).
lying without rhyming is uncomfortable but not impossible (again, rudimentarily, think glass-breaking-high soprano: possible but difficult for most and some pitches the vast majority of people can’t reach).
rhyming/rhythm without lying is also uncomfortable but not impossible (rudimentarily, a tongue twister).
because of this, angels can’t sing. though they enjoy the melodic vocals of others.