Invincible season 4 ending and post-credits scene explained: What does Mark's decision mean?

Warning: Major spoilers ahead for Invincible season 4 episode 8.

Although we had to deal with William’s recasting, Invincible season 4 was an altogether action-packed adaptation of the Viltrumite War Saga, with the episode 8 finale leaving plenty of questions as to what’s next for Mark and co.

As the show’s long-awaited big bad, Thragg lived up to the warnings franchise creator Robert Kirkman gave us ahead of the season, saying how he’d be a "threat that far exceeds even Conquest and anything that Mark has faced".

However, from what we know from the comics, there’s plenty more to come now that Mark’s back on Earth. Including the state of Mark and Eve, Nolan and Debbie’s relationship, Robot (Rudy) and Monster Girl, Thragg and the other Viltrumites, and plenty more, here is the full explanation for everything major at the end of Invincible season 4 and some of what we'll expect for season 5.

Spoilers ahead for the Invincible comics and potentially season 5.

Invincible season 4 ending explained: Why did Mark say yes to Thragg?

The big deciding moment comes at the end of Invincible season 4’s episode 8 finale, after Thragg appears in front of Mark and reveals he and the other Viltrimutes have been on Earth since the Viltrumite War; after all, Mark very reluctantly says yes to the Grand Regent’s terms of letting the Viltrumites stay on the planet amongst the humans in exchange for peace.

The reason that Mark says yes to Thragg at the end of Invincible season 4 is the same as the comics: he knows full well that going to war again with the remaining 37 Viltrumites whilst on Earth would end in defeat, and the endless bloodshed of the human population.

Interestingly, the TV adaptation of Mark and Thragg’s big talk goes in the same way as it originally did, but with a couple of key differences.

In the comics, Thragg’s reveal to Mark that he’s on Earth happens as soon as Invincible returns home at the end of issue #77 — making it so Nolan is there with them both, as well.

However, Invincible’s season 4 finale makes it so Thragg doesn’t appear until after Mark has been home for some time; with this change, though, the show’s creators took the opportunity to have Mark’s fear of Thragg manifest throughout the episode — seeing the Viltrimute leader via hallucinations killing his loved ones, including Debbie, Eve, William, and even Cecil.

As a result, when Mark finally sees Thragg for real, realising the Grand Regent is not a hallucination, it makes his decision to surrender to Thragg’s terms even more difficult. The snippets of bloodshed Mark saw during the episode happened in the comics as well, but they were far more brief.

By making these a central theme throughout the episode, though, we got a more definitive and understanding look at the trauma he went through — now that he’s gone up against Thragg and understands what he and the other Viltrumites are truly capable of, making him much more terrifying from a viewer’s perspective as well by the time Mark sees him at the end.

Do the Viltrumites return in Invincible?

Thragg and the other Viltrumites end their time in Invincible season 4 by blending in with the Earth’s population to breed and start slowly rebuilding their race, with Viltrum’s Grand Regent saying Mark and the other heroes won’t hear from him again.

However, as the Invincible comics have shown, season 4 won’t be the last we’ve seen of Thragg and the remaining Viltrumites in the Amazon Prime Video adaptation. The next arcs of the comics after the Viltrumite War focus more on Earth-centred stories compared to before, but Thragg, Anissa, Kregg, and the other Viltrumites do return eventually.

The Viltrumites do not appear right away during the comic’s next arcs, but we expect them to at least make appearances in Invincible season 5.

Invincible season 4 finale end credits scene: What does Thaddeus's message mean?

During Invincible season 4’s end credits scene in episode 8, a posthumous message left to Allen from Thaedus reveals to the Coalition’s new leader the existence of the perfected Scourage Virus — also insisting he would use it to kill all Viltrumites, even if it affects humans on Earth due to their similar DNA, along with Mark, Nolan, and Oliver.

After Nolan learnt of Thaedus’ role in nearly exterminating all Viltrimutes with the original Scourge Virus, it was unclear as to how far the ‘Great Betrayer’ would go in his goal to exterminate the whole race.

With this reveal, Thaedus’ message implies that even killing all humans is worth eliminating the remaining Viltrumites to guarantee peace for the rest of the planet. As of right now, however, it’s unclear as to whether the series adaptation of Allen will share the same sentiment in Invincible season 5.

What happens in the comics?

In Invincible issue #78, despite some of the differences when adapted into Invincible season 4, Allen finds out about the improved Scourge Virus in mostly the same way as his TV show counterpart.

As expected, Allen spends the following issues feeling incredibly conflicted about using the virus and the risks involved. With the ending of Invincible season 4 starting Allen on this same path, we expect the Scourge Virus to become the next big arc adapted into Invincible season 5 — hinting at lots of conflict between Mark, Nolan, Allen, and Oliver ahead.

Do Nolan & Debbie get back together?

At the end of Invincible season 4, Nolan (Omni-Man) and Debbie aren’t back together, but the two heading off to Talescria makes it likely they’ll do so next season — just like their comic counterparts.

Compared to the source material, where Debbie simply abruptly broke up with Paul and got over Nolan’s betrayal after a tearful exchange, shortly after he and Mark returned home, the TV-adapted version of Debbie in Invincible stuck to her guns and still refused to forgive Nolan. Although Debbie and Paul still broke up off-screen by Invincible season 4’s ending, it was still far more amicable than in the comics.

However, in order to see Oliver, Debbie chose to leave Earth and travel to Talescria with Nolan to check up on him. As of season 4, Debbie’s walls, which she’s put up around Nolan, are coming down a lot slower than they did in the comics, but are coming down nevertheless; we predict they’ll indeed be back together by the end of season 5.

What happened to Robot (Rudy/Rex) & Monster Girl?

After getting trapped in the Flaxan dimension in episode 3 of Invincible season 4, Cecil, Donald, and Sinclair’s attempts in the finale to retrieve Robot and Monster Girl end in failure.

The portal Sinclair had built does open to another dimension, the monstrous tentacle creature that came out made them realise the job was too dangerous to pull off; this means Robot and Monster Girl need to find their own way back.

In the comics, both Monster Girl and Robot do find their way home eventually, but it’s uncertain how it will be adapted for Invincible season 5 just yet.

Invincible season 4 is streaming now on Amazon Prime.

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