The Last Airbender

I despise the Momtara interpretation generally, because it reduces Katara to a role that was thrust upon her, one she didn't choose, and one she clearly doesn't want. She doesn't want to be the Gaang's mom. She wants be their friend, their sister, she wants to be goofy and a kid with them. She exhibits motherly tendencies because she felt like she had to fill Kya's shoes after she died, and over the course of the show, she learns that she doesn't, that she can in fact be a kid when she's with the rest of them.

And you know who teaches her that? You know who teaches all of the Gaang to remember that they're children, because that's one of his roles in their lives?

Katara: [Happily.] I haven't done this since I was a kid!

Aang: You still are a kid!

Zuko: [Angrily.] You're just a child!

Aang: [Calmly, tilting his head to one side with a somewhat confused expression.] Well, you're just a teenager.

Was it this kid, maybe? Who gives her (and all of them) something back the war has robbed them of?

This boy is nobody's Dad.

Aang: That one kind of felt hot.

Zuko[Very angry.]: Don't patronize me! You know what it's supposed to look like!

Aang: Sorry, Sifu Hotman.

Zuko: [Raises his arms to his head, and throws them down back, and shouts in frustration, as Aang cringes.] And stop calling me that!

Aang: [Cut to the gemstone as Zuko runs toward it. Aang raises his arms.] Well, don't touch it!

[Zuko stops and Aang catches up to him.]

Zuko: Why not?

Aang: Remember what happened out there with those spikes? [Turns to look at the side and raises his arms again.] I'm just very suspicious of giant glowing gems sitting on pedestals.

Zuko ignores the Avatar and picks the sunstone, as Aang's eyes twitch.

Zuko: That's cute, but this isn't air temple preschool. It's the real world.

Zuko: [Sarcastically.] Okay, we'll be sure to do that, guru goody-goody.

Zuko: [Sighs and stops walking.] Look, I know you had a really rough childhood, but we should really focus on finding Aang. [Continues walking.]

Toph: This is the worst field trip ever. [Sighs and continues walking.]

And neither should he have to be.

He's a boy. Sixteen years old. He's currently learning what means to have friends, because these are his first friends.

Mai and Ty Lee were Azula's first, but the Gaang are his, and they're the first people he really experiences something like normalcy with. They're regular kids when they aren't busy bending all four elements.

Let him be regular with them.

He's already on his way to become Fire Lord, having more responsibilty given to him than anybody his age should have. Aside from really not behaving like a Group Dad (because, again, he's currently figuring out how to behave around people his age), he also shouldn't have to.