The hole demon didn't do Tsukasa any good. It took away all his friends and family, making him believe it was his only friend. The hole demon is Tsukasa's abusive ex, and we're ready for this conversation. Amane keeps fussing, "Tsukasa, you've changed so much since you left." Of course, he's been brainwashed. He just got out of an abusive relationship, and in fact, he hasn't fully recovered; the demon is still inside him and remains to this day. Amane must deal with the hole demon not as something that has become a copy of Tsukasa, but as something that was his brother's abusive ex and which simply forced Tsukasa to change into the person he became.
Potential for AUs where Tsukasa makes these contracts with someone powerful enough to fulfill them, but who asks for this in return. All sorts of crap. And Tsukasa endures, and Amane doesn't get it, and only maybe later, and maybe tries to save Tsukasa from abuse. Tsukasa literally sold himself in exchange for Amane's medicine. Tsukasa is literally a sacrificial boy, and how cursed that can sound. The line of thought is quite correct, because kannagi is a reference to girls who were forcibly married. They had a potion to cloud their minds and make them submit, as Sumire, which was once said to be a reference to some kind of drugs they pumped into girls so they, like... wouldn't resist. It's such a dark topic, by the way.
By the way, I don't particularly like the demon human forms; for me, it's fine with tentacles and eyes. Although, of course, the image of Muzan in both male and female forms is vibey. The same tyranny and greed, hidden behind a pretty face. I've seen how people like to draw the entity as a cruel mature woman.
Tsukasa is a sacrificial boy, no matter how bad that sounds. Aida didn't draw Tsukasa on a plate like Ciel solely for censorship reasons. I think Tsukasa is truly just food, a sacrifice. He's literally drawn among the food, but being little for the sake of appearances, so it's an adequate metaphor. How many times has Ciel been drawn as food... what do you think, Tsukasa isn't food? I hope the entity never told Tsukasa he's so delicious, because if Koyuki the gourmand (the third mystery) says that, he'll have mind break again.
Tsukasa in living au: 😏😎☺️ yes, I am, I'm your candy, I'm delicious
Tsukasa in canon: ☠️☠️☠️☠️