I'll leave it alone here directly, but the whole thing is bothering me the more I think about it. So now we have a merged Sentry that isnt merged anymore. The ease at which Fat Cobra dispersed of the Void is troubling to say the least. Where was this guy during Siege and other storylines where the Void was a major threat. A couple of panels and the Void is handled. Seriously?
Also, please get rid of the red and black costume and the black hair. Hate it.
Fat Cobra didn't eat the Void. Fat Cobra extracted and ate the tiny bit of Voids negative energy, which was messing with Sentrys mind. Sentry also stated that he is still trying to figure out how he functions now. He had a slip-up. The next time we see him (which will supposedly happen soon) he'll probably be in control.
These aren't my theories. This is what I saw in the comic and what was also confirmed by the writer on Twitter, when someone asked him about Sentry.
Sometimes I wish that there is one scene in the comics... one page... which completely explains the relationship between Bob, Sentry and Void in full detail. Instead Marvel keeps it incredibly ambiguous.
I personally like that, because it makes the character more interesting. But I can also only say that, because I've read every single Sentry appearance multiple times, tried to read between the lines, connect the dots and so on. If other people have not done the same, then they're left wondering: "What the actual **** is going on with this mess of a character?"
I also like to think, that Marvel has an in-house wikipedia about their characters for the writers. And I like to think that Sentrys wikipedia mentions a couple of specific things: reality warping, paranoid schizophrenia, split mind. Schizophrenia means "split mind". Sentry doesn't have multiple personalities, which so many readers seem to believe. Instead Marvel has straight up used the term "schizophrenia" and split him in half.
So in the end of the day Bob is a paranoid schizophrenic, who warps reality. The Void is the devil he imagines to see / to be. And he is unwillingly more specific about it by imagining the Void to be the complete opposite of him. If Sentry saves someone, Void kills someone. If Sentry is good, Void is bad. If Sentry is golden, Void is dark. If Sentry is positive, Void is negative.
And that's what we also saw in Agents of Wakanda. Some of that negative energy was affecting the Sentry. Fat Cobra extracted that small amount of negative energy and Sentry was okay again.
Could Fat Cobra extract the full Void and eat it? I highly doubt that. Not only because that would be an insane amount of negative energy, but also because in the end of the day he would still not heal the Sentrys split mind and the Void would keep returning. Schizophrenia can not be cured.