User blog comment:St0mX/ Natsu & Dragon slayers aging theory discussion v2/@comment-7418318-20150817055355

I don't have much to say about the aging, since there's too little information. But I have something to say about the bonus question:

"How come Natsu is the only dragon slayers (we've seen so far) being able to "absord" something other than fire and remember the technique to be able to use it later like his Dragon Lighting Roar."

He's not. Gajeel has Iron Shadow Dragon and F-Rogue had White Shadow Dragon. From this we concluded that any sufficiently developed Dragon Slayer (or at least the 1st and 3rd gen) can do it, if they put enough effort in it. Wendy might do it too, but so far she hasn't been in a situation where it was do-or-die like Gajeel or Natsu in their respective battles against Shadow/Rogue and Hades.

I'm not sure if Gajeel ever re-used the Shadow DSM, but F-Rogue very clearly retained it's use permanently after killing Sting in the alternate timeline.