Laurie Weathermay-Foxgrove and Gennifer Weathermay-Foxgrove are heroic NPCs from the Dungeons & Dragons setting of Ravenloft. Identical twins, the two are the self-established heirs to Dr. Van Richten as the foremost monster hunters within the Demiplane of Dread, with their particular focus being on publishing the Van Richten's Guides that assist others in battling the creatures of the night.
When Dr. Van Richten was functionally killed off at the end of the Ravenloft adventure "The Bleak House", TSR needed somebody to replace him as their in-universe author of choice. The Weathermay-Foxgrove Twins, nieces of Van Richten's close friend George Weathermay, were created to fill that role. They made their narrative debut in the Van Richten's Monster Hunter's Compendiums; a trio of collective editions of the original Van Richten's Guides, including the never-before-printed Van Richten's Guide to Witches.
Come 3rd edition, and the twins stepped out of their predecessor's shadows more. They wrote three entirely new Van Richten's Guides, covering the Walking Dead, the Shadow Fey, and the Mists of Ravenloft (although that last one was never printed, instead being released to the internet after White Wolf lost the rights to Ravenloft). They also wrote Van Richten's Arsenal, a sort of beginner's guide/how-to book for monster hunting in general. It was here that their backstories and game stats were revealed.
Laurie and Gennifer were born to a minor Mordentish nobleman named Daniel Foxgrove and his wife Alice, the only daughter of Mordent's unofficial leader, Lord Jules Weathermay. Sadly, their mother died in childbirth, leaving them to be brought up by the grieving young widower. As children, they idolized their monster-hunting uncle George Weathermay, and likewise his close friend; Dr. Van Richten, growing up determined to follow in their footsteps and battle the creatures of the night.
Not even early tragedies, such as Gennifer being bitten by a female werewolf named Natalia who had seduced George as a patsy to try and assassinate Van Richten, nor George's subsequent withdrawal from the twins, nor Van Richten's own mysterious disappearance, dissuaded them from their goals. At the "present" of the books being written, the two have moved into Van Richten's former shop and been promoting themselves as monster hunters for a period of about five years, although their reputation as amateurs is proving somewhat slow to dissipate. Well aware of their individual inexperience and weakness, they have actively cultivated allies amongst like-minded individuals throughout the Core, including former allies of Van Richten such as Alanik Ray, and they have memorized Van Richten's principles that research, patience and planning are the keys to triumphing over monsters.
Laurie is the more boisterous sister, always eager for action and a skilled duelist. Gennifer is more reserved and insightful, having instead focused on studying Van Richten's library and honing a talent for arcane magic. In 3e, Laurie is an Expert 2/Fighter 3, whilst Gennifer is an Expert 3/Wizard 2.
Unbeknownst to either twin, they have not gone as untouched by the darkness of the Demiplane of Dread as they believe.
Firstly, George Weathermay has distanced himself because he is convinced that Gennifer is a latent infected werewolf, as a result of Natalia's bite; he has no idea what will trigger her transformations, but knows that Natalia both knows this and can force her infected progeny to transform whenever she wishes. As such, he has dedicated himself to finding Natalia, forcing her to reveal this information, and then killing her. Whether or not George is actually correct in this belief is presented as a "Dread Possibility" - a bit of flexible canon that may or may not be true as the DM prefers. This may stem from the opening fiction to The Book of Sorrows netbook, in which George uses a rare flower (and Gennifer's reaction to it) to confirm her infected state.
Secondly, they are unaware of the existence of Lord Wilfred Godefroy, the ghostly Darklord of Mordent - and, more importantly, they are unaware that he has their mother's soul amongst his legion of ghostly minions, which he is using to force their father to serve him to protect his wife's ghost.
In 5th Edition
The Weathermay-Foxgroves return in 5th edition, now part of a notable monster hunter's network that includes themselves, the now-still-alive Van Richten, Van Richten's adoptive heir Ezmerelda d'Avenir, Alanik Ray, and the ghost of Van Richten's son Erasmus. Their backstory is largely the same, but has been tweaked in a few key details - most prominently, their dad is the dead parent now instead of their mom, although Godefroy is still using their dead parent's ghost to blackmail their living parent into serving him, and they realized Natalie was a werewolf before she attacked and outed her to their uncle, rather than being inspired to take up monsterhunting themselves when they were almost killed by Natalie and he saved them.
Also, according to the one piece of art in the book that depicts them, they now look African, despite the Mordentish being characterized as "Anglo-Saxon" in appearance in general and the Twins specifically being described as having "creamy complexions, dark hair, and icy-blue eyes" in their writeup in Van Richten's Arsenal.