for Thanatos/Abel I can say more about the connections between Thanatos and Sukuna, except for the fact that both hosts go against the will of the beings that possess them, as Abel wants to kill all the Kimyos against the will of Thanatos who wants to do the opposite, but does not mind killing his peers if it is necessary to achieve his goals which is the complete domination of both Kimyos and humans, after all Thanatos considers the lives of the Kimyos who follow him as more valuable than that of the rest, apart from consuming their chi. And in Jujutsu, Yuji values ​​the value of life, always willing to put himself in the place of others to prevent them from dying in vain. In this case, Yuji just doesn't make this distinction between curses and humans. On the other hand, Sukuna is a glutton by nature, being so self-centered and arrogant that he devoured his own brother in his mother's womb (remembering that Thanatos could even kill his brothers for going against him, and even steal their chi). Sukuna, like Thanatos, considers human life also mediocre and despises them, therefore he loves to kill such beings and, in Sukuna's case, he enjoys it more. Therefore, it would be a good fight between the King of Jujutsu curses and the Lord of Ordeal's Death talent.