It strikes me as odd, that Titania and Oberon discuss the number of children Chise and Elias will have, even if there is a limit on her life. Elias and Chise seem to be perfectly content with their relationship, that is in my opinion platonic at best.
To me it seems that a Sleigh Beggy's Offspring, mixed with the blood of a fae, be it a half or full blooded fairy, would be unimaginably powerful.
Chise is the child of two mortals who had the sight, and her father seemed to possess some abilities as well. If she were to reproduce with Elias during the last three years of her existence, she would give birth to another mage or Sleigh Beggy.
What is your opinion? I would love some feedback