Video games are considered canonunless they contradict content in some other Forgotten Realms publication.
The Reaper is a pivotal character in Neverwinter Nights: Hordes of the Underdark. His realm is accessible to the player via the Relic of the Reaper, which is described as having come into the player's hands while they were in the Plane of Shadow after the fall of Undrentide in the second game. During the first half of the game, he serves the same purpose as the Stone of Recall in the original campaign, drawing the player into his realm if he or she dies and reviving them as long as they have a Rogue Stone. Players can also use the Reaper's realm to set up a network of portals so they can mark places and then return there by passing through "the Gatehouse" as the Reaper calls it. During Chapter 3, the player finds out the Reaper has been under the control of Mephistopheles the whole time, commanded to do the archdevil's bidding because he holds the Reaper's True Name. The Reaper informs the player he or she can command him to let them return home if he or she finds his True Name as well. He does not openly say it, but the Reaper does not like Mephistopheles and only serves him because of the power of his True Name. In the end, once the player retrieves the Reaper's True Name, Hecugoth the Abandoned, he admits that he enjoyed serving the player, but also states that they will never again meet. With that, he opens a gate to the final battle and ceases conversation.