Appearance and abilities
Falion was a cold, long-faced Kandori with dark, glossy hair. Falion was quite strong in saidar, in her group of Black sisters she was among the strongest, just a few levels under Liandrin herself. She stands 5'5 tall. In fact, she is quite strong for an Aes Sedai, stronger than many Sitters.
Falion's strength in the WOT Companion is given as 17(5), a high ranking level; she is strong enough to Travel.
She was willing to use the Power to torture anyone, even to death, but was dispassionate about it. She only cared whether they gave her the answers she wanted.
Born in 873 NE, she went to the White Tower in 889 NE. She spent seven years as a novice and six as Accepted, being raised Aes Sedai in 902 NE.
She ran away to Ebou Dar as a novice and knows of the existence of the Wise Women of Ebou Dar. Her brief stay in Ebou Dar was not pleasant. she was caught and returned to the Tower.
Though outwardly cool, inside she was full of anger and slights. She was contemptuous of others' faults, but ignored her own. She considered only other Whites as good company, and even then could find fault with any of them, particularly in their logic. She even thought the Forsaken behaved illogically.
After fleeing the White Tower in Liandrin's group, they went to Tear and worked for the Forsaken Be'lal. They captured Elayne, Egwene and Nynaeve and tried to trap Rand al'Thor just after he released Callandor. After this fails she fled to Tanchico to try and steal the male a'dam from the Panarch's Palace. This plan was also foiled by Elayne Trakand and Nynaeve al'Meara.
They did not manage to retrieve the stash, and eventually began to believe it did not exist. They confronted Elayne and Nynaeve over the Bowl of Winds; they failed, and Ispan was captured. Falion was shielded by a Forsaken (probably by Moghedien under the control of Moridin) and then given to Lady Shiaine as a punishment. The shield was set in such a way that it would dissolve over time. Lady Shiaine tortured her and kept her as a servant and allowed Daved Hanlon, another Darkfriend to use her for sex as he willed. Shiaine was happy to have an Aes Sedai to command, though only punished Falion because she herself would have been punished for disobeying orders.
Meanwhile Falion recuperated some of her ability to channel. So Falion and Hanlon come to an agreement of exchanging information with each other, while keeping up appearances that Hanlon was using her, though he was not. Hanlon himself did not want an Aes Sedai angry at him.
This ruse was discovered however and Murellin was allowed rights over her as well — though Falion mentioned that this arrangement was only when Hanlon was not present.  Falion asked Hanlon for something that would make Murellin sleep through the night as well.
Captured by Elayne
After her shield dissolved, Falion was involved in the unsuccessful kidnap attempt of Elayne Trakand. She was captured, along with Lady Shiaine and the other Black Ajah sisters involved, and was being held in the Royal Palace dungeons in Caemlyn.
The Last Battle
She was rescued from her cell by Mellar. She managed to escape from Caemlyn and was at large until showing up in the valley of Thakan'dar with Duhara Basaheen, where she faced a circle led by Aviendha, who killed both with the One Power.