After watching Peter carry Lena away, Tony felt a sense of relief. Everything had been extremely high pressure, from Rhodey frantically calling him, to the last-minute press conference, to the endless amounts of press begging him for answers; all of it was squeezing his head too tight. He wouldn't be surprised if his brain popped out. Now, Peter was frustrated with him, and for valid reason too. Something inside Tony had snapped in half like a twig, forcing a series of aggressive words on the young girl who had trusted him with her care. He wondered if that trust had changed after the tense encounter.

Rubbing his eyes, he watched as Peter left, hopping into a car he had probably called for himself. The kid was finding a comfortable place at the compound, which was something that Tony had always hoped for. He had anticipated it happening sooner, but Peter had interpreted a serious offer as something that it wasn't, and it turns out Spider-Man would officially become an Avenger at a later date. For now, him and the Siren would be New York's fan-favorite vigilantes.

Having a partner would be good for his mentee. It could be someone that would keep him in check. Tony liked the idea of Peter having someone with him while fighting crime rather than going at it on his own, and someone with so much power over others would almost make the job easy. Plus, there was an odd tie that Lena had to the boy. Maybe it was because he was the first one she interacted with, or maybe it was because she had a crush on him, but they clicked particularly well and he was the only person that Lena didn't blow off. Every human that crossed her path she shied away from, putting a strong barrier between them. It was that way with all of the doctors, her tutor, and even Tony.

Tony wandered in the direction of Cap's old room, the room that Lena had now inhabited. They had cleaned it out a while ago, Pepper kindly returning all of his stuff behind Tony's back, so it had been empty, excluding the basic pieces of furniture. When the girl had finally revealed that she could survive outside of the water, the ghost of the room finally came to life again despite how empty it was.

He was unsure as to why she hadn't mentioned the ability to walk on land earlier, but it didn't matter anymore. Lena could move outside of her tank, and was adapting to human life with ease.

All of the doctors he had hired had sent back good reports. Her progress was extraordinary and unlike anything they had seen before. Even the tutor that they had only started earlier that week said that she grasped onto concepts without further explanation immediately. He had taken a gamble by submitting her application for Midtown, but by the looks of it, she would be completely caught up with Peter three weeks from now, possibly sooner.

He had cut some ties to secure her identity and custody. His lawyer was a smart man, getting the social security number, the birth certificate, and the adoption papers had been a piece of cake compared to the chaos that had been his life since his fight with Steve. It was refreshing to see some paperwork that he actually wanted to read and sign, and saying that Pepper's 'sister' had tutored her at an advanced level was what secured the spot to take the entrance exam. All she had to do was pass it.

For the first time since she had moved in, the door was closed. He let his head fall into the corner of his hand, leaning on the wall beside the door and knocking lightly. It was highly probable that she had no idea what the knock meant, but he could always explain it to her if he had to.

"Who is there?" she said in her small, raspy voice.

"It's Tony. Can I come into your room?"

"Yes."

She was lying on her bed, her face staring at the ceiling. He had only visited her when she was with Peter, so he had no idea if this was normal. Sometimes when he walked by he heard her talking to PET, the AI that had been specifically tailored to her needs. Lots of the human mannerisms that she had questions on could be answered in a direct way, and he was glad she was making good use of it.

"Hi, kiddo."

"Hello," she sat up, hugging her knees to her chest. She was a tiny girl, but when she curled up she somehow looked even smaller.

"Is there anything I can do to make your life easier?"

She shrugged, still cautiously staring at Tony. Her eyes were wide and silver, avoiding eye contact but still looking at him nonetheless.

"I...take your well-being very seriously. The only thing I want is for you to be safe."

There was a chunk of silence, him not knowing what to say, and if Lena wanted to say anything, she didn't know how. It was strange how he wanted her to be safe, but a major part of keeping her protected was to send her right into danger. Sometimes what was best was not always what was easiest.

"Yes," she finally said, "I am...doing...my best," he saw the concentration in her voice as she spoke, thinking about each word before getting it out. She met his eyes, a small tear falling down her face, "Thank you."

"Yeah. Anything for you," Tony lifted his hand and let it fall on her shoulder, hoping she would find comforting in some sort of way. "I've been working on blueprints of that pool. Let me know if you have any ideas. If you find an image you like online, ask PET to send them to me."

He saw a smile from her for what he realized was the first time, "Really?"

"Yeah. Anything you want," he just wanted her to be happy. Tony was slowly starting to acknowledge that he felt the same way about Lena that he felt about Peter, but doubled. It wasn't that he didn't care for Peter - of course he did - but he was now this girl's legal guardian, and held responsibility for her. She was his.

His.

Was this feeling paternal?

He had thought about having kids before, but never for an extensive amount of time. It had always freaked him out, but this teenager had dropped into his hands, and it only felt natural for him to take care of her. His discussion involving her custody had gone surprisingly well with Pepper, and now legally Lena belonged to them.

"I'm going to hug you, is that okay?"

She wiped another tear from her eye and nodded.

Daughter.

He hadn't heard her voice inside his head since she told him her life story. Peter had quickly explained to her that it was more difficult for her to read into some minds, and that Tony's was particularly difficult, but hearing her say the word, a word she had just learned, was affirmation.

Daughter.

…

Mr. Stark left, the energy in the room more uplifting than when he had first entered. Lena had told him that she cared, reassured him that she would not stay upset for long. The anger that had accompanied him grabbing and yelling at her would pass easily, as she was his daughter and she wanted to forgive him.

In her former culture, there was no such thing as a daughter, except for her. Technically, they were forbidden. They were all sisters, each born from one another. Her biological parents had been killed, so she never had an opportunity to be their daughter. She was certain they were somewhere, there souls happy to see that she had found a proper home.

Finding this home came with its consequences. There was no way she could ever return to the Atlantic ocean. They would find her as soon as she came in contact with the water, luring her back to their dwelling to kill her. The power they possessed was strong, strong enough to lure their half sister.

If Peter was with her they would kill him too.

It did not matter, though, because there was no reason to return to the sea. Mr. Stark was building her a pool, made to her liking, and she now watched 'Planet Earth' nearly every day, reliving what it would be like to swim in the salt again. A small part of her was tempted to return, but it outweighed her desire to be with Peter.

She was so close to being able to tell him. Every fiber of her soul wanted to explain to him how badly she wanted to connect with him, to press her lips to his. Ultimately, it was his choice. Kissing a seiren was a contract, and he had to know what it meant before he tried. It was good that he had not tried to as of yet, but it worried her constantly that he would and she would have to kindly reject it until she was ready.

After she was ready, though, he may not be.

A kiss from a seiren was a lifelong agreement. It meant eternity, which was a complicated concept for any mortal to try and understand. Eternity was why a seiren was forced to kill her peirasmós. The kiss from a seiren meant that its receiver could spend that eternity with the person they loved the most, and it gave the seiren complete control over their aging. If they so desired, they could live a full life of youth, or they could age normally, getting older and older.

It would be punishment for their race if their grip on eternity was exploited. The seiren were the fountain of youth that Juan Ponce de Leon had journeyed for so intensely. It was how he eventually met his demise.

Of course, a peirasmós bond was mutual. As of currently, Lena practically full reign over Peter's thoughts. Once their lips locked, it would be a shared. He would be able to tune into her thoughts as she did with him. It would be stronger than it was before, and they could turn it off and on whenever they liked.

If Peter wanted eternity, he could have it. It would bring an asset to their crime fighting capability. They would be one step ahead of every challenger they faced. She could never pressure him to do anything that he did not want to do. She loved him too much.

Love was strange. For her first 63 years, it had been a mystery as to how her mother could give her life for her peirasmós and her child, but the more time she spent with Peter, the more clear it became. The steady process of forgiveness had begun way back when she had gotten a glimpse of Peter's dazed face, and had flourished. She empathized with her mother.

She was her mother.

It was why Peter saw them every night, same as she did. Her sisters had always loved to torment her with the reminder of their betrayal, but when they had slept side by side, his arm around her, it had been a clear night's sleep. Their love overpowered her sisters' hate.

She pinched the under part of her arm, a reminder that she had no way of knowing if he wanted the same. She knew he cared, but eternity was a long time, and it was likely he would be resistant to the idea. The only thing she could do was try and explain.
Once she had the words, she had a plan. Fortunately she did not have to solely rely on words, but speaking the explanation to him was how she wanted to present it, and if she needed to show him through his mind, she would.

She would do whatever it took.

AN: Hi everyone, so glad you're enjoying this story. If you would be so kind as to comment any thoughts you might have, I would love to know what you think! Thanks, Allie x