Against my better judgement I've decided to contribute to this discussion.

I have experienced some of King Asmodeus's suffering. My path is somewhat unique, and my ultimate spiritual goal is fusion with him, so experiencing his memories is common for me, and many of them are deeply disturbing.

The trauma transfers were not fully intentional. During a phase where I was particularly one with him, a state I have since lost due to mental health issues, I would receive vivid memories of his torment almost every single time I meditated. These sessions were often emotionally devastating and at first they upset me very deeply and for days or weeks at a time. Sometimes it upset King Asmodeus too; I think our emotions blended.

The traumas are now my traumas: I already have PTSD, and now I have flashbacks to his traumas too. Since I first started receiving the memories, I've learned to carry these burdens (and my own bodily traumas) more like he does, and my ability to cope with the PTSD symptoms has greatly improved.

Nowadays, the memories I receive tend to be much more mundane--working with other practitioners (sometimes I even get verifiable information), debating politics with other demons, that kind of thing. When traumatic memories do arise, I can usually handle them, and King Asmodeus and I will talk about them together. Sharing memories like this is incredibly intimate.

I don't recommend asking a demon to share trauma like this unless it has some important relevancy to your spiritual path or unless you have trauma and want to bond with a demon over traumas.