Not much is known of the Brill twins, as they only appeared in The Opal Deception and The Time Paradox. What is known is that they did not particularly like their employer, since she made up a lot of rules, such as not looking directly at her (Opal claims that it is bad for her skin), bowing to her, having to prepare her food without touching it, not thinking too loudly within ten feet of her (she claims to be able to read minds, though this is disproved when Merv thinks that Holly Short is prettier than her, and when Scant thinks that Opal has a cuckoo flying around her head), etc. They would have deserted Opal if she hadn't promised them Barbados when she was queen of the world, and she would also add the twins to her vengeance list. They have also been on many talk shows due to the fact that they were twins, rare among The People. In fact, Mervall and Descant are the only pixie pair currently residing in Haven. They are "almost" celebrities. They were featured on the talk show Canto, PPTV's highest-rated chat show. They were also considering writing a book about how they finished each other's sentences in the Opal Deception. They are not extremely bright, but know how to handle computers with ease. They were mainly the cause of Opal Koboi's failure and easily recognized her insanity when it came about. Near the end of the book, Opal Koboi betrays them by ejecting them out of her Stealth Shuttle.
In the Time Paradox, Scant is imprisoned in a cage with a wild boar for not complimenting Opal's new boots. This is mentioned by Merv as he is about to extract Artemis' brain fluid. Afterwards, when he is released, Opal mentions to Merv that she believes Descant may have a crush on her, and could he please tell him that she is unavailable. And as they climbed the steps of the Fowl Manor, Opal scuffs her new boots. This does not go unnoticed by Scant, who mutters "I got locked in a cage with a boar because of those boots, and there she goes, scuffing them without a second thought!" afterwards, when Opal fails, and notices her ruined boots, she tells them "that she is very upset, and needs to blame someone." It is unknown what happened to the Brill brothers, but it is simply written that they didn't run fast enough.
Since they are twins, they look exactly alike, except there is a slight wideness in Merv's brow. Merv is also smarter than Scant.