+-------------------+ | twins | Druid Queen Ayani Darkthorne | |
King _____? --- Queen _____? (murdered) | +-----------------+ Lavender Queen Valerian (aka Darkthorne)
We know that the mother of Princess Lavender and Queen Valerian was a direct descendant of the Druid Queen, Ayani. We also know that the Queen and her King were murdered (poisoned). Lavender was trying to find out what had really happened, which made Geoffrey, the royal adviser, nervous. He convinced Valerian that her sister was somehow involved and got her banished. Lavender tore The Heartseed in half and went to the dreariest place she could think of, Briarheart, and Princess Valerian ascended to the throne.
At about the same time, Geoffrey convinced Valerian that the Chugawugs were to blame, as well, and got her to banish them. A third moved to Wugachug and went back to their care-free roots, a third became Thugawugs, and the last third followed Lavender to Briarwood, to continue their job of defending the royal family by defending the only member of it they could get near.
When Lavender took her half of The Heartseed to Briarheart, the seed grew into Briarheart Palace, a copy of the palace in Sanctuary, but influenced by the darkness in Briarheart, and that in the heart of Lavender, who now became known as Darkthorne.
There was also a story that Lavender had been kidnapped by the Shadow Talon Clan, but we do not know if this was before or after her banishment, or even if it really happened at all.