Given scene/plot descriptions from movies or TV shows, and given a specific question about the scene, summarize the question into a title

[Q]: I'm a bit confused about a scene in How To Train Your Dragon. When the Vikings reach the nest, they open holes and the dragons are flying away. Why didn't they do that in the first place and wait for the humans? I mean, they had input/output ability from the nest (they could fly to the village to steal some food). Could it be that the queen kept some dragons as "prisoners" and only a subset of the dragons were going to the village, so that they are doomed to get back in the nest, so that they didn't lose their friends (just a thought, not a clue of this in the movie)? I was wondering if someone could explain this to me or if it really is a plot hole in the story.
[A]: Why didn't the dragons leave their lair earlier?

[Q]: In The Flash season 4, Thinker forces Barry to come out of the speed force and thus creating 12 different metas who were exposed to dark matter in the bus. Does he know about the respective powers of each meta beforehand or did he create the metas according to his need?
[A]: Does the Thinker know about the power of metas he created

[Q]: In Flash season 4 episode 18 (Lose Yourself) Devoe attack star labs and take the powers of all bus metas. He even takes away the power of Killer Frost. He could easily take the power away from Barry as he was laying on the floor or he could absorb his power too. Same in the case for Cisco. So why didnt Devoe takes Flash's power? Is it because Devoe can only absorb the powers of the bus metas?
[A]:
Why didn't Devoe take Barry's power?