How Is Mantis Star-Lord’s Half-Sister? Explained

How Is Mantis Star Lords Half Sister

Peter Quill was kidnapped by Yondu when he was only eight years old, and for most of his life, he knew Ravagers as his only family. This changed with Guardians of the Galaxy Vol. 2, and he met his biological father, a Celestial named Ego. In Guardians of the Galaxy: Holiday Special, he learned that Mantis was his biological sister. Some fans who haven’t been following the story more closely are wondering how it’s possible for two beings who clearly belong to different species to be blood-related. Due to that, we’ve decided to explain in a bit more detail how Mantis is Peter Quill‘s biological sister. 

Mantis is Peter Quill’s aka Star-Lord’s half-sister because they share the same biological father, a celestial named Ego. Despite belonging to different species, both Mantis and Star-Lord are Celestial hybrids since Ego fathered both of them. This is because Ego searched the Universe and impregnated numerous humanoid species in hopes of having a child that would inherit his powers and help him to achieve the so-called “Expansion” in an attempt to remodel the Universe in his own image. 

Now that we’ve covered how Mantis and Star-Lord are related, it’s time to explain in a bit more detail as well as the biology behind it. If you’re interested in more, stay with us and keep reading!

Star-Lord was fathered by a Celestial named Ego and possibly had millions of siblings across the Universe

The first thing we learned about Peter Quill, aka Star-Lord, in the very first Guardians of the Galaxy movie is that his mother died, and he was seemingly kidnapped from Earth by Yondu and his Ravagers crew. 

Star Lord and Meredith Quill before her death

Peter’s mother died due to an aggressive brain tumor, and the rest of his biological family from that point onward was forgotten. We never met his biological father, but his origin was hinted at in subsequent MCU movies when he was able to hold the Power Stone without being killed and when it was revealed that he is a hybrid of some powerful albeit forgotten and ancient race. 

Quill holds the power stone with minimal damage

In Guardians of the Galaxy Vol. 2, we meet Ego, Star-Lord’s biological father, and we learn that he was actually a Celestial looking to kickstart the event called “Expansion,” but to do that, he needed one more Celestial, as he believed that all other Celestials are long gone. 


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The easiest way to get a Celestial is to make one yourself; of course, Ego created a humanoid avatar of himself and started exploring the Universe, impregnating numerous alien species in the hopes that one of his children would inherit his Celestial DNA. Meredith Quill, aka Star-Lord’s mother, was one of his targets. But in theory, Star-Lord has millions of potential siblings across the Universe since Ego has been doing his routine for who knows how many years before his ultimate demise. 

The sad thing is that most of Star-Lord’s siblings are probably dead since Ego hired Yondu and Ravagers to deliver those children to him. Yondu and Ravagers didn’t know what Ego was doing with these kids until Yondu started strongly suspecting that he was killing them. 

Ego children death

And it was true when the children failed to manifest Celestial powers. Ego would kill them. The biggest evidence for this is the fact that the Ego’s planetary form is lined with the skeletons of his own children that he killed in his ruthless pursuit of power. This was also one of the reasons why Yondu refused to deliver Peter Quill and why he remained hidden from Ego’s radar for all these years. 

Mantis is Ego’s daughter despite not having Celestial powers 

When Guardians of the Galaxy arrived at Ego’s planet, they met Mantis, an empath in the service of Ego. What they failed to realize at the time was that Mantis was also Ego’s biological daughter. This is because Ego treated her as a servant instead of his own daughter. 

Despite being a Celestial hybrid, Mantis likewise failed to manifest her Celestial side, and you’re probably wondering why she was left alive. Despite not being a Celestial in the true sense of the word, Mantis was still extremely powerful and useful to Ego as she was the only thing that was able to calm him down and lull him to sleep in his frustration while he was searching the Galaxy for Peter. 

Who was Mantis’ mother? 

We never learned who Mantis’ mother was, but we know that she belonged to an insectoid species that Ego visited in the past. Mantis was kidnapped in her larva form, and it’s quite possible that she never had any contact with her mother. This is was she was socially awkward and dependent on Ego and why she had a hard time figuring out normal social interactions as she spent most of her life in isolation living with Ego and taking care of his every whim. 

We also don’t know whether Mantis’ mother Shared the same fate as Quill’s mother. 

How are Star-Lord and Mantis biologically related? 

Under normal circumstances, it would be impossible for Star-Lord and Mantis to be biologically related due to belonging to two different species that are vastly different from each other, primarily because Mantis belonged to insectoid species. However, due to Ego, being a Celestial, he could create an avatar of himself in almost any form he wanted, and due to cosmic powers, he could reproduce with almost anything that was capable of reproduction in the Universe since he could emulate the reproductive abilities of almost any kind of species out there. 

Ego and Meredith Quill

Mantis and Star-Lord are related because they share a biological father and his Celestial DNA, and their other parts, which they have inherited from their mothers, are completely incompatible and unrelated. 


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It’s important to keep in mind that as a Celestial, Ego had nearly infinite powers at his disposal, and the fact that he managed to father countless children shouldn’t be so shocking. The guy was a living planet, after all. 

Are Mantis and Peter Quill (Star-Lord) siblings in the comics? Are they related at all?

Mantis and Peter Quill are not siblings in the comics. They are not related at all. This is because their stories and origins are vastly different than those of the MCU. Mantis is not Ego’s daughter in the comics. She is the daughter of Gustav Brandt and Lua Brandt both of whom were mutates. Mantis herself doesn’t have a drop of Celestial DNA and blood in her as she is also a human mutate, the one of Kree origin.

Star-Lord was fathered by a human woman and a Spartax royalty named J’Son. As you can see, it would be really difficult to make them siblings in the comics as both of them have complicated lineages.

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