Right in front of our faces
So I've been thinking about self-eating a lot. Not only because it's weirdly on brand with everything in Claudia's arc (drinking her own blood, treating her own body basically as dark magic parts just for other people's metaphorical consumption, at least in her head, rather than for her own desires) but also because... Why, y'know? Why have this be a thing, why reserve it for the third arc, an arc wherein with the Archdragons gone Aaravos' main goal will be to dismantle the Cosmic Council?
In some ways, I think I was so focused on Aaravos' side of things—the easiest way to get revenge on the Stars (since they don't care about the destruction of their creation, not really, according to him) would be to kill them but he, for whatever reason, cannot do that—that I was missing the obvious other side of things.
Aaravos asks in 7x08, "Are you watching?" but wouldn't it be really bad for him if they were? What is stopping the Cosmic Council from transporting Aaravos to the same place they took Leola and permanently killing him, since permanently killing a Startouch elf is something we know the Cosmic Council, uniquely, can do? He couldn't stop them before when he was more powerful than he is now as a 'Fallen' Star.
Aaravos' plan hinges on eventually getting the Stars' attention, and they are presumably still at their full power, just no longer involved with Xadia. He is seemingly never concerned, even when making the choice to live and plot against them, that the Stars would just kill him the way they did with Leola.
Or maybe, perhaps, he already has a reason that they can't.
As he collapses in tears at Leola's trial, Aaravos' chest star is complete and right side up. After, presumably, 100 years of weeping, his star is inverted and the centre piece is missing when the Merciful One comes to see him.
The reason I brought up self-eating is because we see it's used as a form of chasing immortality, even beyond what Kim'Dael does. I've long speculated that Aaravos purposefully carved out his chest piece, whether to place it in something or to help create dark magic. He may not have done anything with it, even if it was on purpose, but I wonder... if he ate it, in order to ensure that the Cosmic Council couldn't kill him.
This is especially noteworthy since from what we see of Leola's trial, her destructive glow begins in her chest star and then spreads to her fingers, and the destruction of Aaravos' mortal form is radically different.
This doesn't really make sense. Leola was destroyed while in her mortal form, given that moments before she'd been living and interacting with things on earth, just like her father. Aaravos' destruction stems from the bite mark at first, but then begins elsewhere that's entirely separate (the foot) and never broaches the hands. Leola becomes entirely light, while Aaravos' body seems to be shattered, and does bear a striking resemblance to how dark!Callum crumbles in the 2x08 dark magic nightmares.
Furthermore, when Leola is killed and her star energy is sent down (for lack of a better description), we do see a symbol of a star being inverted, despite that not being a part of her character design.
We also know that Aaravos' body being destroyed differently in 7x09 isn't due to dark magic use, at least not in terms of his body. As of season seven, he hadn't done any dark magic in his new body, which is a soft reset. However, we also know that dark magic affects your soul/spirit (6x06) which would, presumably, be the same no matter the body in this case. Therefore, the reason Aaravos' body might've crumbled (beyond differences in execution style) might be because of the dark magic he's used that created a permanent hole in his spirit/self, and one that Leola, of course did not have.
I also think some of this in my head is connecting to the ideas of sacrifice. Other characters, especially parents, can sacrifice themselves in TDP canon in hopes of a better future for their children / the next generation (the three queens, the archdragons, Harrow, etc). Aaravos divorcing himself from the ability to sacrifice himself, especially after thousands of years with no daughter to speak of (until Claudia, but on her in a second), purposefully robs himself from the ability to make a meaningful contribution to the cycle. Death, permanent death, provides meaning and consequence, both things he's seemingly devoid of.
Sacrificing his ability to die (his heart) and at least, in theory, reunite with his daughter / no longer exist without her to ensure he can 'avenge' her is a hell of a thing, after all. And on a certain level, that seems like his endgame goal regardless. Even if all the above speculation is untrue and wily, unless he can execute himself, in destroying/killing (?) all the other Startouch elves, he will be alone and eternal... forever, with no way out, carrying only the pain of his child's death and withering satisfaction at punishing her murderers, unless he decided to eventually change.
Like I said: a hell of a thing.