WMG / How I Became Yours: Rise of the Agni Army

Mai is back because she's now The Undead.
It seems unlikely (within the previous fic) that Katara would let her live even by a hair. So, Sho took his sister's body and either made her a vampire (the photobucket account DOES have a picture of some characters as vampires), a zombie, or a lich.

Mai is back, but as herself from the original show.
Death restores her to her normal self, and, having her memories of the first HIBY, she proceeded to save Zuko from whatever is controlling the entire cast. They're in the Spirit World now, as Diaz hasn't updated since November of 2010

Lilith will bring her parents back from the spirit world.
So far, Lilith has been set up as our likely protagonist. There may be a point where she will learn about how Azula was brought back from the spirit world, and so Lilith will somehow go to the spirit world herself to bring her parents back for the final battle.

Kuzon ends up married to Ling.
Because the only other main character girls are his sister and his cousin. This would continue a Double Inlaw Marriage pattern from the first HIBY, if Lilith marries Poe (as conjectured below). Then, in the third installment, Diaz can mix it up a little bit more by having the spawn of both unions marry each other. Kissing Cousins would not even begin to describe it...it would be beautiful.

Lilith will end up married to Poe.
Because there's no other boy besides her brother to hop into bed with. Not that that has really stopped her before...but still, it would put off even some of Diaz's fans if that happened. The funny thing is that, given that Lily and Poe are the two kids who look most like Katara and Aang, and since their union probably means that Katara and Aang will now share grandchildren, HIBY effectively becomes a Kataang fic in disguise like "The Avatar and the Firelord" was a Rozin story in disguise. Then again, it also makes HIBY a Zukaang fic in disguise...and Katoph...and Tuko...okay, I'm just gonna quit while I'm ahead...

Miracle dies.
It's a prerequisite for being a Snow White Lobzula/ Leonardo Di Caprio Sokka/Princess Yue clone. And, hell, her mom's already done it once.

At least one of the children will die in a Heroic Sacrifice.
Whether they will be Killed Off for Real or brought back from the spirit world like Azula in the original depends on whether Diaz will want to make the ending bittersweet just for the sake of being bittersweet, or happy just for the sake of being sugary.

The possible outcomes of Lilith against the bullies...
  • She comes to her senses just in time and spares them.
  • Miracle and/or Kuzon stop her with counter-bending, and possibly a Cooldown Hug.
  • She kills them and either repents for it, or is told she did the right thing and becomes a Designated Hero like her mother.

A Legend of Korra character will appear
Hopefully Amon so he can curbstomp everyone.

Amon is the real power behind the Agni Army
Mai and Sho are big parts of it, sure, but Amon is where it all started. Sho's story of his sister being bloodbent nearly to death by a psychotic, entitled waterbender who can't be persecuted because she's royalty would definitely help the Equalist movement gain ground, because nobody really wants to live under people who can kill you horribly any minute if they feel like it and can't be called to task over it.

The revolution really took hold in the Fire Nation, as they're the country that has to live under a bloodbending Fire Lady, and as it became more widespread and organized, it became more militant and started calling itself the Agni Army. Mai and Sho took direct command of the Fire Nation Equalists, now the Agni Army, as they were Fire Nationals and symbols of the grievances nonbenders had against benders (and while Sho is a bender, he usually forsakes that and Fights Like a Normal). Mai, being the proactive girl that she is, decided to start by removing the people at the root of the problem- Zuko and Katara.

In the HIBY-Verse, Mai and Sho are behind the Equalists

Like the above, the Agni Army is a militant Fire Nation Equalist branch, but Amon isn't behind it, because Yakone was never stopped (that's what happens when the Avatar dallies around with his girlfriend instead of doing Avatar stuff) and so Noatak never became Amon. The undercurrent of feeling that led to the Equalist revolution, however, was still there, but it was instead picked up by Mai and Sho, who used the story about how Mai was nearly killed by Katara to garner sympathy for the movement. The Equalist movement exists in its normal form in the Earth Kingdom, but in the Fire Nation the grievance against the Royal Family meant that it evolved into the Agni Army, and is now a full-fledged rebellion.