we get to play with sansion now

the first line's way off from the desired iamb and I'll try'n show ya why, natasha
They get LOCKED / UP AF / ter SUPP
(starts out with an poetic foot of annapest then followed by two stressed syallables making a spondee foot then finally an iamb. read the line out loud and hear where the stresses fall as you read aloud.
I'll mess up your rhyme to fix the meter, so you'll have to tinker with something else next. . .the woes and hazards of meter and rhyme)
they're LOCKED / a_WAY / when SUP_ / per's DONE
(suggested line with iambic meter)
(second line actually reads well in my opinion but doesn't scan in iambs. I'll show ya)
and GET / TOLD SOR_ / did TALES
(starts out with iamb then a spondee and ends with iamb. Not a bad line but if you want iambs one suggested way. . .
with TALES / to FEED / they're FEARS
(third line is in perfect iambs but read vague to me until after several passes, but then I'm old and slow too *sigh* clairty might be helped with something akin to. . .)
LIES / of DEV_ / ils IN / their BLOOD
the last line that you'd already mentioned didn't sing to you scans odd too. here's why)
DEAF_ened / by DEM_ / ons' WAILS
(or it could scan as. . .)
DEAF_/ ened by DEM / ons' WAILS
(the second one seems to be the way it reads aloud but I reckon could go either way. either way you weren't happy with it
an example with aforementioned headless iambic foot:)
WHIS_ / pered IN / their EARS
They get locked up right after supp
And get told sordid tales
of devils growing in their blood
Deafened by demons' wails
rewritten stanza reads:
they're locked away when supper's done
with tales to feed their fears
Lies of devils in their blood
whispered in their ears.
now hope I've helped and not confused
with all my babbled stuff.
meter's easy once the ear
hears the smooth and rough

monty