The way Grout talks about prince Lacroix actually makes me insane, like
"The information the voices have given me ranges from curious to frightening. The latter case is especially true of one powerful vampire whose name I shall not commit to recording in the interests of self-preservation."
Grout is an ex-psychiatrist from an era where patient abuse was at its peak in mental asylums. (which he misses and laments the loss of, btw) And he is overall incredibly detached and callous towards his 'experiments', so the fact that he comes to fear Lacroix so much and to be this affected by what he gleaned about him from the voices, makes one wonder,
What the fuck is going on in that twink's head?
"I'm thinking again of the particular vampire of whom I spoke previously - who I dare not name for my growing fear. If the voices are to be believed, then my caution is warranted for they speak of his blackest crimes both past and future. More than once I've seen the suspicion in his eyes and heard the distrust in his voice when speaking with me. The fear must register on my face as it is all I can do in these moments to keep from crying out in chorus with the voices."
These lines also tie into my hc that if the sarcophagus did have an elder or an antediluvian in it, it likely wouldn't be Lacroix's first time committing the act of diablerie. For a vampire, especially someone as cynical and jaded like Grout, to mention his 'blackest crimes', I don't doubt it is referring to something far more severe than his manipulations or even his alliance with Ming Xiao. While Camarilla would have certainly obliterated Lacroix for the alliance, I doubt Grout specifically would have found the idea as mortifying as his words suggest his visions to be.
Diablerie can canonically be addictive if performed multiple times, as well. And it could be a possible explanation for Sebastian's gradual loss of composure and his increasing obsession with the sarcophagus. The change in his demeanour after the idea is planted in his head that it could be an antediluvian, is palpable, and although he denies their existence as someone from camarilla would, he is openly perusing the potential menu of his next big feast, if you do hand over the key to him.
Also to call back to the lines regarding his advancement in vampire society being 'unnatural' in opinion of some of the other vampires, and his relative youth for the position he holds, suggest to me that he has found power in less than typically acceptable ways.
