Tyrande, Malfurion, & Illidan
Illidan and Malfurion, believe it or not, are twins. They are night elves that grew up together with Tyrande in the Kaldorei city of Suramar.
So Illidan and Malfurion and Tyrande all grew up together as kids, playing in the woods together, learning to hunt until they got old enough to each pursue their unique calling. Tyrande went to the Temple of Elune, the Goddess that the night elves worship, and became a priestess in the order of the Sisters of Elune. Malfurion was taught by the demigod Cenarius to be the first Druid and Illidan searched for his purpose in the studying of the arcane; magic. Illidan had a biiiiig crush on Tyrande but she only had eyes for Malfurion, and he didn’t even notice that Illidan also liked his girlfriend.
The Leader of the Night elves at this time was queen Azshara and she and her crew of Highborne were messing around with the magics of the Well of Eternity, a huge magical well that they lived by that gave them their immortality and magic but was kind of mysterious, they didn’t really know why it was so powerful, where it came from or what it could do.
As Malfurion was training to be a druid he started to notice that Azshara was drawing away from her people and becoming suspicious and secretive and he foresaw that the magic of the well would cause his people a lot of trouble. Well it did. The Big Bad Sargeras was drawn to Azeroth precisely because of her messing around with the well. It’s energies drew him to her and he corrupted her as he had the draenei. He convinced her to open a portal to her world in the well so that he could come to Azeroth. Led by Archimonde the Defiler and Mannoroth the Destructor his armies invaded through the portal. This is the start of the War of the Ancients. (Spoilers...the well of Eternity is so powerful because it is made up of the blood of a titan, the most powerful titan ever known. Sargeras as a corrupted titan was super hungry for this power and has been trying to capture/destroy Azeroth to obtain it ever since.)
Infernals, doomguards, felhounds were among the creatures that were unleashed upon the Kaldorei. They were losing. Badly. So it’s up to Tyrande, Malfurion and Illidan to save their people. Here’s where it gets tricky, Illidan was messing around with the power of the well himself and that stuff turns out to be very addictive. With the support of Mal and Tyr he is able to control it, kinda, and they go off together to find Cenarius and ask for help. Cenarius gets the dragons, including Alexstraza, to send their flights against the demons and also calls on the spirits of the forest to make an army of tree men (Ancient of Lore et al) to fight the Legion. It’s still not enough. Malfurion decides that the Well of Eternity must be destroyed. This is tough, it is the source of all their magic and their immortality. Tyrande agrees seeing it's the only way to stop the Highborne who are using it to channel the portal spell and let Sargeras through, but Illidan can’t do it. He betrays them and warns the Highborne of their plan. Prepared ahead of time for the attack of Malfurion and Tyrande and allies, the Highborne kill a lot of them as they rush the well and grievously injure Tyrande which sends Malfurion into a rage. He battles Azshara right beside the Well throwing the carefully crafted spells into chaos. The portal explodes within the Well and this causes what is known as The Sundering. Azeroth initially was one huge continent that was torn apart by this massive explosion. 80% of the landmass was destroyed and the rest was split into Northrend, Kezan, the Eastern Kingdoms, Pandaria, the Broken Isles and Kalimdor. Where the Well of Eternity once was is now a vortex know as the Maelstrom which still rages to this day. Azshara and her highborne, corrupted by the energies of the Well were pulled down into the depths and became the naga.
Tyrande became High Priestess of Elune as the former head of the order was killed in the War and named her successor, and so is the new leader of the Night elves. Malfurion, Tyrande and Illidan survived the sundering and made their way across the water with what was left of their people to Mount Hyjal where they found with horror that a lake there had been befouled by the Well of Eternity's dark energy. (Illidan had filled several vials with the Well's water before it was destroyed and was trying to make a new well.) For this he was imprisoned in the caverns below Hyjal in the barrow deeps (for ten thousand years) and guarded by the sentinels led by….badumdum...Maiev Shadowsong. They were too afraid to try to destroy this new well however after seeing what happened when the Well of Eternity exploded. Sooo, they planted a tree in it and exiled all the remaining highborne that didn't turn into naga. These are your blood elves. (To this end, they created the World Tree, Nordrassil, which they pledged to use to protect the Well of Eternity and the night elves themselves. Alexstrasza, the Life-Binder, grew the tree herself from an enchanted acorn of G'Hanir. Nozdormu, the Timeless, placed an enchantment upon the tree: for as long as it stood, the night elves would never die of old age or sickness. Ysera, the Dreamer, linked Nordrassil to the Emerald Dream. Through the tree, she would slowly rebuild the world. However, to maintain the Emerald Dream, she needed consciousnesses to roam its eternal pathways. To sustain it, all the druids agreed to sleep for centuries at a time, despite the years they would lose, and be linked to the Emerald Dream forever.)
Illidan is often seen as Athas was, willing to do anything to save his people and then corrupted through that desire. He believed that the Legion was so powerful that they would need the powers of the Well to fight them while Malfurion and Tyrande thought it was pure evil and better off destroyed. This became a recurring theme in Illidan’s life where he constantly made sacrifices and horrible alliances to gain incredible power because he thought that nothing else could stand against the Legion. He felt that no one understood him but his motives were always to defeat the legion. He lost his eyes when Sargeras took them and gave him instead the ability to see all kinds of magic and fel energies. He consumed the hearts of demons to gain their power and became a Demon Hunter.
The next time the three were to be together was 10,000 years later when the Legion again attacked their world in the shape of Arthas and the scourge. Tyrande believed that they would need Illidan's power so against Malfurion's wishes she went to free him. The Sentinels fought her when they refused to release him and she slaughtered them O.O Malfurion does not trust Illidan, seeing in his addiction to magic a threat that will never go away, but Illidan wanted to prove he was wrong about him. He meets Arthas in Felwood and fights him, they are evenly matched and they pause to talk. Big mistake. Arthas’ plan is to corrupt Illidan with the lure of great power so he tells him about the Skull of Gul’dan (yeah that Gul’dan) and Illidan takes the bait. He finds the skull and consumes its power becoming half-demon, he also uses the power of the skull to make new demon hunters like him. Malfurion and Tyrande are horrified by his transformation and even though he uses the power to defeat Tichondrius and his demons that are trying to destroy the tree, they banished him from the forests forever.
In order to defeat the Lich King and the Burning Legion Illidan has pretended to ally with them, made alliances with naga and demons and indeed become part demon himself, as a result the relationship between the three is forever shattered. (More on Illidan later in his own Lore Moment.)
Tyrande and Malfurion are now husband and wife and rule the night elves together, although Malfurion does sleep a lot....