I came up with a plan. The only way I could seduce the Grim Reaper was if the Grim Reaper was around.
I started off with Ollie and Cassidy Purdue. Some of them had to die in order for Grim Reaper to appear, so I decided that Ollie will be that victim.
The most certain death in The Sims 4 is Death by Hunger, so I decided Ollie to starve. It wasn’t an easy task though since I felt really guilty watching Ollie being more and more uncomfortable.
After more than 2 Sim Days, Ollie died. Grim Reaper showed up and took Ollie’s soul.
After the Grim Reaper finishes his job, hold shift, left click on him and select ”Add to Family”.
As a Grim Reaper, you can go around town and socialize with other Sims. But, you cannot do most interactions that are related to fulfilling Grim’s needs and emotions.