User blog comment:Marco the Marine Admiral/Theory: Evilness Can Lead to Power-up for Dragon Slayers/@comment-24066070-20140628165509/@comment-7418318-20140628181639

That an interesting thought. That really might be the case.

My theory behind the 1st, 2nd and 3rd gen is that 2nd gen get their initial power quicker but that their "power-gain-curve" goes flatter as they progress, while 1st gen start out slower, but gain power quicker.

Third gen of course get's the best from both sides, since they are 1st gen enhanced by Lacrima like 2nd gen.

And I also think that "true" Dragon Slayers (1st and 3rd) gain more benefit from using their emotions.

Of course that's just my speculation.