The knowledge of the death is a power not to take lightly. As the reaper, you´ll gain insight that can make or break the game. The town will either praise you, or fear your.
Death is Only the Beginning
As the Reaper, surrounded by death, only your own survival matters. And while you might want to help the city, by sharing who got murdered, you´ll become a prime target for the night dwellers attacks.
When a person is killed, most importantly at night, you´ll see the true and unaffected card that the person had. This outshines a lot of the Town Investigator roles, but also sets you in a grave deal of danger. An example: If a person is a neighbor to The Imp, he is seen by The Seer as a werewolf, but you can see right though the imps foul smell when that players die, and see the pure card. You can therefore be a spectacular addition to the town team. But just as well, be the most prominent target by the werewolves.
To work around this fear of getting killed, or to simply play the reaper in a different light, you can assume the identity of a fallen player. If a card like The Seer, or another important town role, is killed at night, you can take over their identity and lean on the town protection you. But beware: the town will know about the Reaper.
When you play the reaper, you´re always walking a fine line between holding your knowledge to yourself, and over-expose your finding. The reaper can be played in many different way, and no one way is the only right one. Just remember that you own survival is the only thing that matters, the means to get there is no priority.