Both parents have essence, though neither is over 80.
So you waited to take a spouse until you'd imbued a champion and gotten him or her through a ludicrous number of battles?
I'm not scoffing, I'm just curious about what happens when you seriously postpone starting your dynasty.
 
Well, I'm not terribly in a rush to start a dynasty - it just doesn't really do anything when you get down to it.  So yes, I can be more discriminating.  But no, I don't need to get into a "ludicrous number of battles".
 
Actually, it's ridiculously simple - you imbue your prospective mate.  This gives them 3-4 essence, depending on the faction you play.  Then all your essence bonuses kick in.  That's potentially on the order 500% more unit essence.  If you throw in a single level up or two (which, for a level 1-2 champion, is something like 3-5 fights), it's not hard to end up with around 20 essence or more on a champion.
 
Perhaps you misread?  NEITHER is over 80.  BOTH are LESS THAN 80 essence.  I believe in the game in question, the sovereign had ~36 essence (after multiple imbues) and the queen had 22.
 
In my current game, I have a daughter with over 700 essence at level 1.  All I do is pump intelligence.  She can solo any army, let alone create one instantly with summons (ends up with a combat rating of 600 - and she has NO gear on, which would raise CR higher if she did).  The father has 30 essence, the mother has 21.
 
There's no reason to begin a dynasty at the outset as the AI does (it also, apparently, STARTS with a spouse).  And with kids that can, at level 1, instantly summon a cr 600 army, teleport anywhere I reign, and regenerate mana in battles... why the hell would I want to marry them off?