Wrap Your Head Around This

Question

George loves watching Helmet Teens. It is a show about a group of four teenagers that each have a special power when they wear a space-helmet. Each helmet has their own own unique symbol, activating its own special ability to the person wearing it — and it only works for the teens! Their names are:

• Ethan;
• Walter;
• Fred; and
• Aris.

Unfortunately, the television was playing up; during the past week, the volume was randomly turning off and no sound would play, or the channel would randomly switch off, or the entire TV would do just that.

One day, during an episode of Helmet Teens, the TV screen turned black — but the sound kept playing! George was trying to figure out what episode it was, until he realised it was Episode 1.

This is what he heard:

"Greetings, humans. I am the Helmet Space Robot, home to a world of helmets. Much as you are humans, my kind living on my home planet are Helmets. Our planet is called Helm, and now I need you to help me. Listen carefully, as I will not repeat one word I say:

Our world has been destroyed by war, with the powers of the helmets battling each other. Now, I am the last Helmetkind alive. My home planet existed in the past, but not anymore!

As a consequence, for each of you, I have the four main helmets with the forces that used to govern our planet, so we can be remembered. Put these on, and you shall have powers beyond human strength."

This was the Helmet Space Robot, of course. Then spoke the four teens. George was waiting to hear their voices, but then the sound cut out and the subtitles appeared on the screen.

"Mother nature! This helmet is so down to me!"
"Cool! Everything else seems like me under the bridge!"
"Holy flame! I am so up myself, right now!"
"Knock me off my feet! I'm walking on myself!"

Somehow, George was able to tell which teen was telling which line, and which teen was receiving which helmet. (He was just beginning to actually enjoy the show, to his surprise, when suddenly the TV blew up and he had to tell his parents to get a new one.)

How did he do it?
What was the helmet each teenager was given?
What was each of their special abilities?

Bonus 50 rep bounty reward if (and only if!) you have answered the three previous questions:
What is the secret message hidden in Helmet Teens${}$?

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The title seems unrelated... but it is a clue.

Edit:
Forgot to mention, this puzzle was inspired by @Keelhaul's "Unwelcome" puzzle. If you liked this puzzle, I suggest you check the other puzzle out if you think you haven't seen it.

Answer 1

So, the first thing I got was that

Helmet Teens is an anagram for "the elements".

Further, just like the

pairs of bolded Space Robot's words are different by only one letter, the four names are different from the names of the elements by only one letter: earth (Ethan), water (Walter), fire (Fred) and air (Aris).

If we

replace the word "me" in what the four "teens" are saying, we get: "Mother nature! This helmet is so down to Earth!" [Ethan] "Cool! Everything else seems like water under the bridge!" [Walter] "Holy flame! I am so fired up, right now!" [Fred] "Knock me off my feet! I'm walking on air!" [Aris]

So now we know who got which helmet.