[Those would be "always" and "where else would I put it", but since the questions go unasked they also go unanswered. Instead he looks on proudly as the heir appraises the designs, nodding when he's addressed again. He's given it a lot of thought!]

There are a handful of reasons. For one, such a castle would seem to fit in well for the period and culture this realm seems to be based in. Western castles are also far more well known for these sorts of high towers, which make perfect roosts for fiends who dominate the skies. [Like, eventually, himself.]

It also carries a terrifying and ominous air about it, a perfect fortress for dastardly abominations like myself and imposing figures like you.

[There could also, possibly, be Sonia influence in here, somewhere.]