Question about fire breath

[Salokin18]

I tamed a dragon with awesome stats but only 814 HPs, so I'm wondering how that will affect his breath atttack. Is the amount of damage done by fire breath determined by the dragon's current hit points or the current percent of its max HPs?

For example:
If a dragon's current HPs are 500 and its max HPs 1000 (50% of max) will it's fire breath hit the same or harder than a dragon whos current HPs are 400 and it's max HPs are 800 (50% of max)?

 

[Kazumi the Wild]

It is based on current hit points - A Greater Dragon with 999 hit points hits about twice as hard with its Fire breath as a GD with 500.