"Dragon’s lungs to emit flames, dragon’s scales to melt the flames, and dragon’s nails to engrave the flames. That is an ancient spell that transforms your body to that of a dragon’s." -Happy, Episode 01
 a magic that you wanted to have fire dragon slayer magic
Actually, Mashima has said in interviews that Natsu and Lucy are based off of Haru and Elie from his previous manga Rave Master, who ended up getting married in the end.
And Mashima has also stated that if the two were to have a child her name would be Nashi, “Na” from Natsu’s name and “shi” from the Japanese way of saying Lucy, which is Rushi.
If statements from the author himself isn’t enough to say that Natsu and Lucy are canon, then I don’t know what is.
If you ship any of the following, please reblog this so I can follow you, please and thank you:
NaLu (Natsu x Lucy)
EreMika (Eren x Mikasa)
AruAni (Armin x Annie)
LeviHan (Levi x Hanji)
GaLe (Gajeel x Levy)
FlashLight (Flash Sentry x Twilight Sparkle)
Len x Rin
Akihito x Mirai