Question: Just what size relationship would the dragon eggs be compared to the adults? In season one, we see the eggs as being roughly the size of eggplants or a child's football, at the start of Season 7, the dragons thereof have grown to 747 (whale?) size. Just how big would the laying mother have been? Even if she reproduced in the equivalent of a teenage pregnancy, the size of the dragons in past seasons, her offspring would have been dust motes compared to her. If Season 7 represents them fully-grown (and think about it if they are not!), the dragon's biological mother would have been truly gargantuan compared to her offspring.
Answer: The dragon of Aegon the Conqueror, the first king of the Seven Kingdom Balerion the Black Dread was so massive it could attack the megacastle of Harrenhal by itself. Free dragons not locked up in confinement can grow to whatever length it can. This is why Drogon is larger than his brothers Viseriyon and Rheagal.
Answer: In the universe shown in this series, dragons can technically grow indefinitely. They continue to grow throughout their lives. They will stop growing, however if they live in captivity in a confined space. There is therefore no standard size for an adult dragon.
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