Talk:How to Train Your Dragon: The Hidden World/@comment-35838726-20180610170211/@comment-34260863-20180611062458

Really, it does look like Toothless is channeling his alpha mode again in that lightning scene, with the blue glow in his mouth and along his spines. I guess it wouldn't have made sense to introduce it in the second movie if they weren't going to bring it back for the third.

It's either back because he has mastered it, or something really, REALLY gets him mad sometime before this scene takes place. It's also interesting to note that he doesn't have his gear on... but I would SO bet that this bit happens sometime after the battle scene with Grimmel's (Drago's?) ships shown in the trailer. After the Light Fury saves him from falling, maybe even.

...Maybe, after Toothless' fall, Hiccup insists on him wearing the self-operated tailfin again because he just can't handle another close call like all the ones before.