Toothless isn't tame, you can't really ever ... do that, to a dragon. My dad had a Thunderdrum called Thornado that he released back into the wild to take care of some stray babies of the same breed, we see him sometimes in the ocean with the others of his Tidal-class. He's got a shoal of his own, now.

[ Old Thornado, that guy was great. Loud as fuck, obviously, but great. Hiccup smiles without realising, because talking about dragons? Is never rude with him.

Seriously, it could be three in the morning and he'd probably be okay with it. ]

Me and Toothless met up in secret, we got to know each other away from everyone else so it was a little touch-and-go for a while. We had to figure out a way to communicate. Night Furies are the smartest and fastest dragons, he understands everything I say and I don't have to mess about mangling Dragonese in front of him, which is lucky because I can't really differentiate between 'yak' and 'hug', which can get a little bruising.

Dragons can be insanely dangerous. I don't think that changes no matter where you go, but that doesn't mean they immediately default to it.