Hrm. I will concede I have not seen a human murdered in front of me, and I am about as normal as Wedensday Addams on these things, so I'll take your word for it.
Human emotions tend to elude me at times...
I think it will help if you add a bit more character traits to Thaumo, so that he isn't defined solely by his neediness.
I may not like that particular trait of his, but I think he'd be a better character all round if he had some more depth to him.
Maybe a show of vulnerability that explains his clingyness (fear, trauma, whatever), or some interest in something that he is passionate about.
(There is a million videos on youtube on writing, and a ton of books. Try Brandon McNulty on YouTube. He has some good pointers on writing. And writing good characters. He's a published writer for a reason.)
(There are many ways to be clingy too, for that matter. Most yandere's tend to be. But if you use Sebastian from Particles of Reality as an example of the ideal yandere; he knows when to back off, but he never -really- backs off. Or the pink-haired guy in...ah... 14 Days With You. He is also clingy, but manage to come off as charming despite it.)
I look forward to see how it turns out.