Her first memories are of Ego, him cradling her in his arms, tickling her, telling her that he loves her.
Her first memories are of him calling her daughter and her calling him dad.
She doesn't know much, but she knows that her dad is the best person she has ever met. He is also the first person she has ever met, but that's not really something that occurs to her.
She knows that her father is impressed with her ability to feel his emotions. He thinks she can be just like him, and she feels his hope and his pride. She feels his regret and his guilt too, but she doesn't know what to do with those. Instead, she tries to ease his pain. His eyes crinkle up.
"Are you trying to change how I feel?" He asks. She nods, a little embarrassed. He grins at her.
"Don't be embarrassed, kid," he says, "that makes you powerful, just like your old man."
He spends months teaching her to be like him. He thinks that she could be a celestial like him, that the ability to change the world is deep within her, like his bright, glowing core. He thinks that she might have that power, and his excitement overwhelms her every time she touches him.
Then, the fateful day comes when she should be able to do it. She knows that she should be able to wield the energy within the planet. He expects it of her. This is the day. This is the day that it should happen, but she can't create so much as a spark.
"I wasted so much time on you, Mantis, but you're just another failure." He moves his hand, and summons a tendril of bright blue energy. She runs forward, and touches his hand.
"No," Mantis says, touching him, willing him to love her, to let her go. His look softens.
"You're getting better at that," he says. He places a hand on his chin, and looks thoughtful.
"Maybe you can help me sleep."
"Yes," Mantis says, "I can do that. Whatever you need, dad." His look sours.
"Not dad," he growls, "I'm not your dad."
"But you said-"
"That was before I knew what you are," Ego says, "I thought you might be a celestial, but you're not. You're just another mortal, another failure." She doesn't know what those words mean, but he says them with such scorn she feels tiny, helpless. She feels like she isn't a person anymore.
"Then what do I call you?" she asks, her voice small and afraid. He looks thoughtful for a second, then he smirks.
"Call me master."
She learns a little from each child Ego kills.
She learns a little more about social interaction, a little more about a distant planet she will never visit, a little more about the world she lives in.
It doesn't really matter. She will never leave this planet before Ego engulfs the whole universe in the vast sea of himself, so these things will all be gone before she could ever use the information. She still likes learning things, and she grows up at her father's side, even though the growing is stilted and awkward and her father doesn't act like her father. Even though she calls her father master and lives to help him sleep.
At least she gets to grow up. At least he doesn't kill her. He doesn't kill her like the rest of the failures, his un-children. He lets her live. He will kill her one day, along with the rest of the world, but right now? He doesn't. He lets her live.
That has to be enough.
Ego dies. Ego dies. Ego dies, and Peter lives. He's the next celestial, and Mantis knows where she owes her allegiance.
"How can I help?" she asks. She asks this every day, at every opportunity. She mainly asks it of Peter, because he's the one who inherited her, but she asks the others too. None of them ever react well.
"You don't have to do anything, Mantis," Peter says, sounding concerned.
"No, no, I do. That's what I'm for. I have to help you." If she can't be useful, then she doesn't have any reason to be.
"You don't have to do that," Peter says, "you're our friend." She sends him a confused look, and his softens.
"What did Ego do to you?" It sounds like Peter is angry at Ego for the way that she lived, which doesn't make any sense to her. Ego was the one that kept her alive. She was the failure.
"No, don't blame him, he was good to me."
"He wasn't good to you," Peter says, sounding deeply angry.
"I wasn't supposed to live, but he kept me around." Peter's confusion emanates from him, even though she isn't touching him.
"He killed the rest of them."
"The rest of what?"
"You're my sister," he says, epiphany in his eyes. He looks disgusted.
"No, no," Mantis says, "don't feel bad. I'm not really your sister." It doesn't matter that Ego called her daughter. She was a mistake that he decided to keep around, not a true child.
"I'm not mad at you, Mantis," Peter says, rubbing his forehead in frustration.
"You're not? You're not upset to be related to someone as ugly as me?"
"We gotta make Drax stop saying that," Peter mutters. Mantis looks at him.
"I don't understand. Why are you upset?"
"I'm pissed at Ego. That was so fucked up. You- you deserve so much better, Mantis"
"He didn't kill me, even know I was a failure," Mantis says. She doesn't understand. That's the best that she deserves.
"No, you're my sister," he says, "and I'm gonna treat you like it."
"I need to go," Mantis says. Peter grabs her arm and tries to keep her from leaving. She can feel his emotions. There's anger and there's frustration, but underneath it is a fierce feeling of love.
"Please don't," he says. Mantis breaks away, and she feels her eyes water as she leaves him. She doesn't know what to do with any of this, and she certainly doesn't know how to feel.
Mantis avoids Peter. She knows this, because he seeks her out and she goes wherever she knows he won't be. She just doesn't know how to deal with this.
The idea of having friends is new and strange, but the idea of having a brother, family who loves her, that's stranger than all the rest. She decides to ask Gamora about it. If anyone on this ship knows how to be a sister, it's her, right?
"Mantis," Gamora says, "Peter's looking for you." Mantis nods.
"I know. I'm avoiding him."
"You're avoiding him?" Gamora asks. She sounds confused.
"Yes," Mantis says, "I do not know how to be a sister." Gamora laughs, a little bitterly.
"That makes two of us." Mantis doesn't understand.
"But you have a sister?"
"Yeah," Gamora says, and Mantis can feel her fondness and regret, "I do."
"How do I be a sister?" Mantis asks. She doesn't know how to go about this. She's only ever been a helper (failure, pet, slave). She doesn't know how to be a sister. She doesn't have any frame of reference for this.
"I'm not the best person to ask, Mantis."
"But you are a sister. You are one and you have one. You should be an expert."
"I didn't do a great job with mine," Gamora says. It sounds final, and Mantis realizes that she won't get anything else from Gamora. She'll have to try somewhere else.
Mantis seeks out the only other sister she knows. She seeks out Nebula, and she finds her in a nasty bar a couple planets away. Mantis sits down next to her, and Nebula sends her a confused look.
That's comforting, because Nebula has a cold, hateful glare, and the confused look means that she doesn't hate Mantis. At least it probably means that she doesn't hate her.
"How did you find me?"
"I looked for you."
"Why? Why would you want to find me?" Nebula asks, sounding skeptical.
"Gamora misses you. She wants to be your sister." Nebula sends her a sardonic smile.
"So I've heard." Mantis bites her lip. She doesn't think this is going well.
"Is that the reason you're here, to play messenger?"
"No," Mantis says, "I wanted to ask you something."
"What would you want in a sister?"
"Why are you asking?"
"I am one now," Mantis says, "I don't know how to do it."
"Who's the lucky sibling?" Nebula asks. Mantis has heard the word lucky used sarcastically, but Nebula doesn't sound that way. She sounds at least half genuine about it.
"Peter." Nebula's black eyes widen.
"Ego kept you as a slave," Nebula says, and there's a deep depth of hatred in her voice, something to rival Peter himself's.
"You were his daughter and he kept you as a slave."
"He didn't kill me," she says, and to Mantis, that is defense enough. She could have been one of the skeletons Ego kept in his caverns, but she wasn't. She was useful to him, and he decided to keep her around.
Nebula is quiet for a while, and then she opens her mouth to talk.
"That's what I thought, back when Thanos first took me. He slaughtered my planet, massacred my race, and he took me to be his daughter. But I was just so grateful.
At least he didn't kill me, right? He could have killed me. I thought that as he pitted me against Gamora, as he took my body from me piece by piece: at least he didn't kill me." Mantis feels something deep inside herself. It feels like empathy, like she's feeling Nebula's feelings. But that can't be tight. She isn't touching her.
"You shouldn't have to be grateful for this, Mantis. You deserve better." Mantis feels an anger stirring inside her for Nebula, and she realizes the other woman is feeling the same for her. There's something fierce in Nebula's black eyes, something passionate and caring. They are more intense than anything else Mantis has ever seen.
Mantis wants to feel what she feels, truly. She wants to touch Nebula and meld their emotions, to see if what they are feeling is truly the same.
"May I touch you?" Mantis asks. She has learned from interacting with Gamora that she must ask first. Some people dislike being touched, and more dislike being touched by an empath.
"Fine," Nebula says. Mantis reaches out her hand, and gently touches Nebula's hand. Instead of flesh, she touches cold, hard metal. She can't read emotions through metal. She tries her upper arm, then her shoulder, and she finally gently touches her face. They are all metal, and Mantis realizes that these are not just prosthetics.
"You are made of metal." Nebula flinches back.
"No, no," Mantis says, "it's alright."
"It's not alright, I'm a monster," Nebula says, with something bitter in her voice, "Of course an empath would see that."
"No, no. I just don't know what you feel. I did not know how to react." Mantis smiles shyly at her.
"I like it."
"You do?" Nebula asks, sounding almost hopeful.
"Yes," Mantis says, "it is like an adventure, not being able to read your emotions from a touch. I have to figure it out on my own." It's a little scary, but exciting, not knowing what someone is feeling.
Her stomach feels like the planet she was raised on, constantly changing and rippling. It's turbulent, but in a way that she enjoys. She wants to feel it some more.
"I feel content," Nebula says, "I feel content talking with you. We should do this again." Mantis's heart leaps out of her chest, and she can't find her voice. All she can do is nod.
She hopes that gets her point across.
Mantis comes back to the ship an hour later, and it seems that the others were about to call an interplanetary alert on her. Peter engulfs her in a hug, and she can feel the warmth of his relief and love flow through her.
"We were so worried about you," Peter says, finally breaking the hug. Gamora sends her a glare that's particularly harsh after Peter's hug.
"You can't just run off," Gamora says, sounding more pissed off than worried.
"I was worried as well," Drax says, "I thought someone might have stolen you for their ugly creatures zoo."
"Shut up, Drax," Rocket growls.
"I am Groot," the tiny tree says.
"Nebula does not think I am ugly. She thinks I am beautiful."
"You met with Nebula?" Gamora asks. She sounds surprised, and a little bit excited.
"Why'd you want to see that blue bitch?" Rocket retorts.
"Don't call my sister a bitch," Gamora says, "only I can call her a bitch." Mantis doesn't know what to say to this, like she often doesn't when speaking to the guardians.
Instead of trying to retort, she says, "We had a date." She doesn't want to tell them she asked Nebula for sister advice, because calling it a date is close enough to the truth. Nebula agreed to meet with her again, and Mantis felt hints of the things Peter feels for Gamora for Nebula. She would like the next one to be a date for real.
"I have to give her the shovel talk now!" Peter exclaims.
"The shovel talk?" Gamora asks, raising her eyebrow.
"That talk where you threaten someone you care about's significant other so they treat 'em right, you know?" Gamora raises an eyebrow.
"But Nebula could crush you like a bug," Mantis says. Nebula could crush him as easily as Ego could have crushed her all those years ago.
"I'm your brother," Peter says, "it's what brothers do. We threaten people to make them treat our sisters right, even if we wouldn't actually stand a chance against them." Mantis didnt know that's what brothers are for, but she smiles.
"Thank you," she says, "I think I like having a brother."
Mantis seeks Peter out later that night to try to talk about this more privately. He is lying on the couch in the living area, listening to his music. He sees her, then he rips his headphones out and sits up stick straight. He's trying to look composed, like he wasn't just curled up in a little ball listening to his song about Piña Coladas.
"Mantis, hi," he says. She smiles at him. She knows that she should probably say something before she gets into what she wants to talk about. She knows that people are supposed to make "small talk" but she also isn't familiar with it, and thinks that she'd just make things more awkward. She decides to just talk about what she wants to talk about.
"I do not know how to be a sister." Peter looks a little shocked that she started with something so heavy, but that doesn't throw him too much.
"That's alright, neither does Gamora, or Nebula. I don't know how to be a brother. Neither do Groot or Drax. Lord knows Rocket doesn't know how to."
"Then how will we make this work?" Mantis wants this to work. She wants to stay with the guardians, engulfed in love and friendship. She doesn't want to lose this.
"We're a family now," Peter says. That's not really an explanation.
"Ego was our family," Mantis says, "I do not want that again."
"Ego was blood, but he wasn't family."
"What does that mean?"
"Family are the people who have your back. The people you can laugh with, you can cry with. They're the people you want to come home to."
"Can I touch you?" Mantis asks.
"Sure," Peter tells her, and Mantis places her hand on his. Peter feels warm. She can feel love radiating through him: for Gamora, for his mother, for Yondu, for Rocket and Groot and Drax. She can feel his love for her too, and she squeezes his hand.
"Brother," she tells him. He feels like her brother. He smiles.
"Yeah sis," he says, "welcome to the Guardians of the Galaxy."