Vereesa Windrunner has lost everything several times now.
She lost her oldest sister Alleria to the same Horde invasion that killed most of their family, as Alleria went off to seek vengeance against the orcs and ended up lost somewhere beyond the Dark Portal, never to be seen or heard from again. Her other sister, Sylvanas, was killed by the Lich King's servant Arthas Menethil, and the death knight chose to prevent Sylvanas from even attaining the peace of death, trapping her in undeath.
Worse, when Vereesa lost Sylvanas, she lost her homeland and her people. The high elves of Quel'thalas became blood elves, following Prince Kael'thas on the path to ruin, addiction, and madness and she could not, did not follow. Along with a few remnants of her people, she attempted to preserve what had been thrown away, to keep high elven culture alive even as Silvermoon resided in the hands of those that had abandoned it. Its not surprising that she found love in someone who shared her loyalty to the Alliance, nor perhaps is it surprising that she found it in human arms, as both Alleria and Sylvanas showed a predisposition to humans.
Last of the Windrunner sisters
Vereesa Windrunner comes from a proud heritage, and it can't be overstated that it has suffered greatly over the past few decades. First, when the old Horde led by Orgrim Doomhammer allied with Zul'jin the Amani trolls led Horde forces right to Quel'thalas, and several members of the Windrunners (including Vereesa's father, monther and youngest brother Lirath) died to orc axes. It was the horror of what had happened to her family in the Second War that motivated Vereesa to excel as a member of the Farstriders, but she had joined the order of elven rangers before that, and earned a reputation for recklessness as well as some derision from her fellow Farstriders as being too like a human in her quick temper. This could have been in part because her elder sister, Sylvanas, was at the time Ranger-General and had a human, Nathanos Marris, as her prize pupil. Following the Second War, King Anasterian chose to cut ties with the humans rather than remain in their Alliance, seeing them as too bloodthirsty and short sighted to make good allies, and this prejudice against humans could have made life harder for Vereesa, who by that time had met Rhonin.
Her meeting with Rhonin was in fact her first major assignment as a member of the Farstriders. She would have rather been assigned to track down and kill orcs like Alleria, but fate proved more prescient than she was - in the course of her duties as escort to the mage, she would find herself engaged in combat at Grim Batol against the forces of Nekros Skullcrusher and the Dragonmaw and even eventually would help free Alexstrasza from the control of the Dragon Soul. The simple escort mission had turned into a wildly dangerous adventure, with all the orcs she could shoot, and in the chaos of that mission she found herself moving from disdain to friendship, and then more than friendship, with Rhonin. Neither of them were particularly easy people to deal with, ultimately, both quick to anger and almost conceited about their abilities. If nothing else, it was a union of equals, and in that union she found acceptance that had eluded her among her own people. They hadn't liked each other, but they found that they could love each other.
However, as tragic as the Second War was for the Windrunners, the Third War proved far, far worse, as Arthas' assault destroyed what was left of the family. Vereesa's grandfather was forced to fight the reanimated corpse of one of his own sons, her uncle, and we know what happened to Sylvanas. Vereesa escaped this fate, sidelined by her pregnancy, as her family was destroyed - her two remaining brothers also died in the Scourge, one slain by the reanimated form of the other, who in turn was put down by the survivors of Arthas' destructive march on the Sunwell. To compound her grief, even as she was giving birth the first pangs of the high elven magical addiction began to strike. In this moment of grief, it would have been easy for her to give in to that hunger for magic and take the same path her cousin Zendarin did, and become a blood elf. And it is that moment of refusal, of looking at the life she had created for herself, that led her to not only reject that possibility but to begin her revulsion at the very idea. That revulsion turned into disdain, and Vereesa (who had been taunted and mocked as being too human by the high elves) now in turn rejected the blood elves they had become as insufficiently elven. They had fallen, and she had not. They had lost their way, and she had not. They had surrendered what it meant to be a high elf... and she never would.
Her viewpoint of her people's change was skewed by one of her own family, however, into something even darker.
Burning in the fire until only the essential remains
This led to her role in defeating Sinestra at Grim Batol, after her cousin Zendarin attempted to kidnap her twins. Zendarin viewed Vereesa as having tainted herself by having children with a human, since he shared his race's prejudicial view of humans as stupid, brutish, short lived creatures who were only useful once as cannon fodder against trolls. In the end he died, and the Windrunner family shrank even further. Zendarin's accusations of Vereesa having somehow demeaned herself by laying with a human were echoes by Vereesa towards Zendarin, as she viewed his having become a blood elf as a similar debasement, a great lowering of himself to the level of an addict desperately craving even demonic sustenance. She had feared she could become such a thing, and now she loathed that state and those that have accepted it. Seeing a former family member, a close relative she had even been friendly with, embrace the teachings of Kael'thas to the degree that he was willing to kill her children for more magical power hardened her heart against her former people. To her mind, Zendarin's actions proved that the blood elves were not to be trusted.
Still, while she disdained and even hated the blood elves as a group, she still maintained a connection to Silvermoon and her people. Years later, when Halduron Brightwing, current Ranger-General of Silvermoon asked Vereesa for help against the Zandalari working with the Amani, she led Silver Covenant forces of high elven rangers to his aid. The two of them stood united even against Lor'themar Theron as to Vereesa's place outside Zul'Aman, with Vereesa going so far as to call Lor'themar (her former commander as her sister's Sylvanas' second in command during her time as Ranger-General) a coward. Why she feels this way specifically about Lor'themar is unknown. For that matter, why she seems willing to respond to Halduron's summons is equally unknown, given her disdain for all things blood elf.
When her husband rose to the leadership of the Kirin Tor, Vereesa traveled with him to Dalaran and established a sizeable faction of high elves who had retained ties to the Alliance, the Silver Covenant, with which she opposed the efforts of Archmage Aethas Sunreaver to establish Dalaran as a neutral city and to bring the Horde in as allies against both Arthas and Malygos. However, as Aethas was a mage and a member of the Council of Six, he successfully prevailed over Vereesa's objections. She never forgot them, however, subtly working to subvert the Sunreavers throughout the Nexus War. After her work against the Amani during the Cataclysm, Vereesa returned to Dalaran and her husband's side. And it was in Dalaran that Vereesa first heard of the Horde aggression against Theramore when Lady Jaina Proudmoore came seeking aid. Vereesa went with Rhonin to help defend Theramore, and along with Shandris Feathermoon she took to Dustwallow Marsh to hunt down the traitor Thalen Songweaver. As a result, she was not present when her husband died saving others from the mana bomb.
Vereesa will never forget
And it is this final loss, a loss caused by a weapon crafted by blood elves and unleashed by an orc, that stole the one person who helped Vereesa make sense of a mad world. When he family was destroyed by orcs, she found purpose in revenge. When the Scourge killed her grandfather, her uncle, her two brothers she found the will to endure in Rhonin and their children, and when her people became demon-drinkers who made alliances with the same orcs that killer her mother, her father, her baby brother she held firm.
She, who had been sneered at as beeing too human, was now more high elven than any of them would ever be. She, the youngest of the sisters, was the only one left, and she turned away when others fell into corruption. When her own cousin, her own blood, came to try and kidnap and murder her children she saw the truth laid bare - the blood elves were a mockery, a disgraced remnant, a disease pretending to be her people. Only those few who had resisted could be trusted. Only those high elves who still wore Alliance colors were truly her people. And this union of tainted, fallen elves and orcs had brought what to the world? A bomb so awful it ripped the world itself asunder, a force so devastating that nothing was even left for her to mourn. Worse, her beloved children, the reason she managed to avoid falling into wallowing in demonic magic, would now grow up with a loss like the ones that had carved away at her.
Just as the orcs had raided Quel'thalas and killed her kin, just as the Scourge smashed through the elfgates and destroyed what was left to her, just as Zendarin had tried to destroy her haven, her children, had called what had saved her impure and unclean as he did it. Vereesa's husband died because of the monsters that killed everyone and everything she'd loved, another victim to the lust for power and the orcs who burned the forests outside Silvermoon when she was a young Farstrider. Her actions in Dalaran and on the Isle of Thunder are far from surprising. What is surprising is how effective they've been, how well she's harnessed her outrage and found herself working in tandem with Jaina Proudmoore. Her purge of Dalaran was at once shockingly brutal and completely comprehensive, and her work as part of the Kirin Tor Offensive marks her as a force to be reckoned with.
Jaina Proudmoore is an idealist, forced to come to terms with the possibility that her ideals were misplaced. But Vereesa is purely a wronged person who wants revenge, a violent killer who lost those things most valuable to her. She didn't have idealism to lose it. She had the shattered bodies of her family, dead at orc hands, Scourge hands, and now orc hands using a weapon placed there by her once-kinsmen, now horrible monsters. What did her grandfather do when his son came at him, a shambling corpse? He put that corpse back in the ground. And Vereesa would like nothing more than to bury the blood elven disease.
Still, don't mistake her for an unthinking zealot. Vereesa is cool, intelligent, and even sardonic in turn. Her grief hasn't unhinged her at all. It's only made her more focused and determined. Anyone who mistakes the Ranger-General of the Silver Covenant for an easy mark to be manipulated by her passions will regret their mistake.
Vereesa Windrunner is dangerous entirely because she is a Windrunner, with the combination of patience and malice the family has always possessed. She has lost much, and she can lay her losses directly at the feet of her own former people and their allies. And having been so forced to endure loss, she is prepared to make others endure it in turn. The Horde may in time come to regret dearly having dropped that bomb on Theramore, and her former people may regret their having constructed it even more so. Because a Windrunner never forgets, and very rarely forgives. Jaina's fury may cool, given time. Vereesa will hate and hate and hate, and never let that hate distract her from precise, measured action.
While you don't need to have played the previous Warcraft games to enjoy World of Warcraft, a little history goes a long way toward making the game a lot more fun. Dig into even more of the lore and history behind the World of Warcraft in WoW Insider's Guide to Warcraft Lore.