In the abandoned timeline where the characters all were shunted into the future, that Vex’halia waited for Stubby to call her back. She harbored deep regret for not looking, having given up after 20 years, and when they called she suddenly had hope for the first time in decades.
But in that timeline, her daughter never arrived.
The Madness of Vex’alia
Vex waited. She waited another decade. And then she decided not just dragons, but dragonborn, ravenite or otherwise, were to blame for the terrible things in her life.
Armed with not only her own Vestiges, but Percy’s, Vex went on a rampage. She slew every dragon on Tal’Dorei, and then Wildemount, Isslyra, and the Shattered Isles. Then Vex turned her eyes to the dragonborn on Wildemount, and found herself face to face with her friends. Vox Machina stood against her.
As powerful as Vex’halia was (with Fenthras AND Cabal’s ruin, as well as Diplomacy), she knew she couldn’t defeat the rest of Vox Machina so she turned to the one creature she knew who could stay death, who could revenge on that Raven Bitch …
Vecna.
Swearing her allegiance to Vecna, Vex killed Grog and Pike and Kaylie (who inherited Mythcarver), leaving only Keyleth. Their final battle was intense, and Vex lost. She’d been weakened by her fight with Grog and Keyleth dealt the killing blow to her dearest friend.
A Death Cult
The rest of the de Rollos were appalled. They spent six generations trying to prove to the rest of the world that Vex was an aberration.
Except. Secretly, in the Ziggurat beneath Whitestone, where the Threshhold Crest from Draconia was hidden, they began a plan. They studied and worked and researched until they determined what had happened. Using the ties with the Kryn Dynasty forged by Vex, they had long been introduced to Dunamancy, and they knew if they could understand the timeline, they could save Vex.
If they could go back, cleanse the timeline of the aberration that caused their insane ancestor, then they would save the de Rollo name and have vengeance. There was, of course, a dissenting branch, who thought Vex was right, and secretly worshiped Vecna.
This leads us to Lady Vex’ahlia Sylda von Musel Klossowski de Rolo III, a many times great descendant of Vex, the first to bear the name since Original Vex’s death. Her mother was convinced Vex had the right of it, and primed her daughter to follow those footsteps. The heir to the generations of anger, Vex III didn’t want to save her ancestor’s name… She wanted the prime-timeline STUBBY to feel their pain.
The Heir to Madness
A follower of Vecna, she used the Ziggurat and the Crest to power her jump through time, landing her on Wildemount in 825PD. For 10 years, she worked in secret, learning from the Soltryce Academy, finding where the items she needed were now, and then when the second war broke out, she left for Isslyra.
Many of Vecna’s weapons were locked away, so under the name Livia Thorne, she aligned herself with Arkhan and Ryo and Victor to weaken the power structure of Vasselheim.
Small accident, though, was that Victor found out something was wrong, and betrayed her. Her plan didn’t quite work out, leaving her underpowered and in need of saltpeter to kill the de Rollos…