Crassus and his REAL son Publios both get what they deserve with their invasion of the Parthian { Persian}Empire. That would be a nice little follow up story when the series ends with the slave revolt crushed.
Allowing the Parthians to draw them far into the desert, far from water, then attacked by thousands of horse archers and Persian Cataphracts, armored cavalry. Crassus is shown his sons head on a spear, retreats leaving all the wounded and surrounded troops to the Parthians. Begs a truce { his surviving troops demand a parley} and is slaughtered along with his entourage .
I recall this occurs while Caesar is in Gaul, and in letters to Crassus, he encouraged the invasion in the East.
" OH sure, easy deal,The Persians are whimps, no problem, you'll be victorious, go for it"