This is genuinely the most emotional scene to ever come out of the series.
BTW, I have a theory for why Eternal Slumber captured Momma Sprout:
We know that Eternal is part of the body of Pandemonium, who Kargob defeated and severed into the seven Demon Swords using a sword known as the Sword of Light.* The very sword that created the universe, according to the official Swords website.
*
Momma Sprout is the Guardian of Light.
When we first see Eternal approach Quest Sprout, he backs off when Momma appears, as if he's afraid of her.
Could it be because her light powers remind him of the battle against Kargob?
Perhaps when they first met, Momma battled Eternal, who got PTSD from her light powers and decided to retreat. However, as time went on, he pretended to be afraid of her, waiting for the right moment to take advantage of her naiveness... (More on that later.)
The villain has successfully captured the main character's mother and imprisoned her in his tower... now what? Will he kill her? Steal her powers? Torture her? Keep her trapped there for the rest of time? It's never exactly made clear what Eternal's end goal is, in regards to the capturing of Momma.
To put into perspective, Cat from Cat Bird Dog was captured by the Wizard and threatened with being turned into a semi-sentient plushie/figurine if Bird and Dog didn't rescue her. She wasn't just being put into a cage; There were actual stakes being planted in that arc.
If the stakes are simply just Eternal Slumber keeping Momma Sprout trapped for the rest of time, it'd be very boring and hollow writing IMO, with the Sprouts' temporary reunion losing a lot of punch. Without any proper stakes, it really seems like Momma wasn't in any kind of real danger in the long run.
My headcanon:
Eternal will kill the Sprouts to erase their powers as well as the entire godly light element so that it can't be used against him and the other Demon Swords. It would be especially tragic, because Bograk, God of Light, presumably died alongside Kargob because they were inside the Demon King and nobody could become their champions with their Godswords.
