• It spends all it's time following and trying to breath-kill any other players at any distance of sight, unless the tamer has it sit on the ground.
• It will also die to it's own breath if it stays in one spot.
• And it does not appear to attack hostile mobs on its own (while tame), just other players.

• 1.21
• 1.20.6
• 1.20.4
• 1.20.1
• 1.19.4
• 1.19.2
• 1.18.2

Planned:

• improved AI
  • not tamed: attack all players
  • tamed: attack everything that hurts the dragon or it's owner
• attack range should changeable through the config #22
• should not die by it's own attacks

added in all active branches and 1.21