If heroic spirits don't age how is Paul going through puberty?

We have a lot of Holy Grails...to wish for things...

NegativeSoul said:

If heroic spirits don't age how is Paul going through puberty?

Nobody ages in the Throne, since it's more accurate to treat them as recordings than individuals when they're in it, but also no summoning system was designed to keep Servants around long enough to make natural aging a major issue -- even in FSN, Gil was heavily sustained by blood sacrifices. It's a definite question whether assumptions about how Servants are assumed to work apply to Chaldea's sustained summons.

gonzomehum said:

Nobody ages in the Throne, since it's more accurate to treat them as recordings than individuals when they're in it, but also no summoning system was designed to keep Servants around long enough to make natural aging a major issue -- even in FSN, Gil was heavily sustained by blood sacrifices. It's a definite question whether assumptions about how Servants are assumed to work apply to Chaldea's sustained summons.

Indeed, Chaldea is actually the odd one out in terms of how summoning works from what I have seen. Giving the Servant relatively easy way to remain permanently present for very long periods of time.