Shandris Feathermoon has been through a lot over the past ten thousand years. A child when the Burning Legion first came to Azeroth, she lost her family and indeed her very home village to the Legion. Effectively 'adopted' by Tyrande, Shandris grew up with a bow in her hand, and following the Legion's defeat she became leader of the Sentinels, the Kaldorei military, when her erstwhile paramour Jarod Shadowsong, who had led the night elves in battle against the Legion, turned his back on their people and walked away. Not Shandris - she has spent the past ten thousand years defending the night elves of Kalimdor. And at present, Kalimdor has become a very hostile place for the night elves.
- As general of the Sentinels, she's been forced to defend the night elves as they've come under increasing pressure from the Horde.
- Shandris is unshakably loyal to Tyrande. Specifically, Tyrande.
- Tyrande's actions have made Shandris' task significantly harder. Her freeing Illidan cost the lives of several of the Wardens guarding his cell and started Maiev Shadowsong onto the path of insanity that cost the night elves their best spies and assassins right when they were needed. Then her diffidence in confronting the Horde threat in Ashenvale (caused in part by Malfurion Stormrage's return and assumption of 'co-leader' status) only made things worse.
Now, Shandris can't turn on Tyrande. She's psychologically unsuited to it. But she can turn on Malfurion, who has spent most of the time while Shandris has been at Tyrande's side asleep. I'm not saying Shandris hates him, because I doubt that's true, but she doesn't have the same bond of affection. That being said, she and he have interacted over the years, and he even aided Tyrande recently in saving Shandris' life when the naga overwhelmed Feathermoon Strongold during the Cataclysm, so I don't think she would move directly against Malfurion out of hatred or rage.
But look at the situation. The Wardens are still in disarray, with Jarod Shadowsong in charge of a small group still in training along with her Sentinels, and those charged with apprehending Maiev Shadowsong. The Horde has pressed the attack in Darkshore (using trolls as cat's paws), in Ashenvale wiping out Silverwind Refuge, firebombing helpless villagers in Astranaar - and how would that resonate with Shandris, who saw her own village wiped out by the same Burning Legion the Horde once served? Seeing the orcs clear-cutting in those same forests, seeing them kill children, would be like a knife in Shandris' chest, pulling her in opposite directions. Loyal to her people and Tyrande, she's still forced to defend them without actionable intelligence, from a base in contested Feralas, while Tyrande and Malfurion seemingly do little to halt the bleeding. Azshara gone, Stonetalon the scene of a Horde weapon of mass destruction, and when Shandris answered the Alliance's call to defend Theramore a traitor from within the city's ranks ended up leading her away - which is the only reason Shandris wasn't in Theramore itself when the Horde dropped another such terrifying weapon.
Following all of this with the recent Horde civil war and the Siege of Orgrimmar, and yet what happens? The Horde retains the lands it stole from the Kaldorei, and even gets to appoint a new Warchief, thanks to the actions of the human king that Tyrande is now also deferring to, instead of leading. Shandris is no racist, but she is a night elf, and has over ten thousand years of life experience, yet she's expected to allow the Horde to continue to exist because someone who will die before he's even one hundred is telling her to do so?
What happens when Shandris has finally had enough? After all, she loves Tyrande like a mother, but mothers and daughters disagree, they argue, they even fight on occasion, and Shandris is the one with the responsibility to lead the Sentinels in war. If her mother won't lead their people, if she keeps deferring to Malfurion and his strange druid obsessions (and remember, Shandris was born at a time when druids were barely even known among their people) or outsider kings, then perhaps Shandris will have to act without letting Tyrande know what she's up to. Using the Huntresses and the rare Sentinel Spies (which Shandris was forced to create because Tyrande cost their people the Wardens) Shandris begins setting up her plan to destroy the Horde once and for all. Since she is loyal to Tyrande and feels affection for Malfurion, even if she disagrees with them both, she won't just seize power, but she's also too canny to count on them approving of what she's doing. Instead, she plans to present them with a situation so far along that they can't do anything about it.
First off, it requires exploring ancient ruins. Horde players get involved when rumors of night elves exploring the ancient magical vaults underneath Eldarath, and move to stop them from getting their hands on Azuregos' hoard. But Alliance players are recruited to be the ones exploring the vaults, and in fact find a treasure trove of artifacts for Shandris' plan.
This leads to several months of a cold war between Shandris' Sentinels and the Horde, as Shandris moves to place seemingly unimportant artifacts in various locations, some of obvious strategic importance, others which seem completely random. Over time, it becomes clear that Shandris is attempting to create a strong, defensible corridor from Feathermoon to Darnassus, claiming control over Desolace and Stonetalon in the process via the various Kaldorei ruins in these areas. At the same time, Shandris walks a fine line, reporting to Malfurion and Tyrande while also recruiting from those elements of night elven society most dissatisfied with their leadership. Former Druids of the Flame who lost family to the Horde firebombings, disaffected Highborne who haven't felt fully incorporated into their people since their return, worgen who have found Shandris much more willing to bring their people into the Sentinels and treat them as respected equals (and perhaps she also promises them her direct assistance in reclaiming Gilneas) - she builds her forces while playing cloak and dagger games with the Horde. Horde players find themselves running quests to try and expose all of this, while Alliance players find themselves divided between supporting Shandris and working to prevent her from destabilizing the situation.
There are other forces, darker allies, that Shandris might be willing to work alongside. Vereesa Windrunner's Silver Covenant can provide useful information on blood elf strengths and weaknesses. Magatha Grimtotem possesses a powerful elemental relic and is probably willing to ally temporarily with the night elves to strike back at the Horde. She wouldn't trust the night elves, and Shandris certainly wouldn't trust her but you can imagine a Grimtotem/Sentinels alliance, especially if it ended the Grimtotem assaults on new Thalanaar.
Underneath Dire Maul, the former city of Eldre'Thalas, a great many ancient secrets of the Highborne await, as well as lore left behind during the ascension of Cho'gall and his ogre favored. Again the Horde rush to prevent Shandris' agents from getting their hands on it, while Alliance players find themselves working to secure it - even if they're starting to feel unsure about Shandris' motives, they've seen the Horde with such artifacts and the lesson of Garrosh isn't lost on them. Better the Alliance have it. Meanwhile, Shandris actually works to allow some Horde agents to penetrate Darnassus and attack the Temple of the Moon while also acting to make sure no harm comes to Tyrande or Malfurion, as she needs to get them to agree to place Darnassus on high alert so that she and her Sentinels can become the defacto power in the night elf capital. Horde players who take part in this reprisal raid may not even realize they've been used until the end. Alliance players who try and stop the Horde similarly just play into Shandris' goals.
Finally, after all the pieces are in place, Shandris makes her move. She activates the artifacts secreted throughout Horde territory and magic itself goes haywire, striking down many of the Horde's spellcasters. She declares a war of retribution and moves to reconquer Azshara and Ashenvale while keeping Tyrande and Malfurion isolated, intending to present them with a reconquered Kalimdor and a destroyed Horde and expecting that while they may not approve they won't throw away a sure victory. What will the Horde's response be? Will the Alliance support her actions, or view them as dangerous? And will Shandris be willing to go further than simply holding Tyrande and Malfurion captive (having had to use some of the treasures of Azuregos' vault to do so, since between them they're the most powerful priest and druid in the world) if it looks like she needs more time to execute her plans? What side will Jarod Shadowsong come down on, that of his one time lover or the leaders who he swore to serve? And what happens if it turns out that the majority of the night elves, whether or not they support exactly how Shandris acted, agree with her that Malfurion and Tyrande have failed in their responsibilities? Imagine if the people rally to Shandris' war, and don't want to stop even after Tyrande and Malfurion regain their freedom. What then?
A full-fledged night elf civil war could be the result, and one that isn't as easy to stop as raiding Darnassus and killing Shandris. It's possible the only way to stop it could be to get Shandris herself to back down, but to do that might require that others admit their own mistakes. We could finally have an expansion where killing monsters and raid bosses, while important and fun, doesn't resolve things and the night elves find their way of life forever changed. Shandris may find herself leader of her people, and at odds with the ones she loves the most, at the same time.
Since Anne's up, let's switch things up a bit. Let's imagine an expansion built around Garona Halforcen.