Disclaimer: I only own the plot and my OCs. Anything you recognize as not mine belongs to Marvel Studios, Disney, and/or their otherwise respective owners.

Author's Notes: So I came up with this a while ago, wrote almost all of it, didn't like it, and then rewrote it all in one sitting. Lmao, that's where we're at rn I guess.

Yes, this is part of yet another series. I really need to stop making those. But, in my defense, I just love the idea of exploring an omega!fem!Peter as the foster daughter of Stony and her relationship with all of the other Avengers, hence the series title.

Anyways, Penny is a victim of CSA in this, but it's not explicitly stated beyond implication and my tag warnings on AO3. So, just like...know that going in, because it is a central point to this story without being explicitly stated.

The title comes from the saying: "Blood of the covenant is thicker than the water of the womb."

As always, I hope you enjoy,

~TGWSI/Selene Borealis

~spider-girl & the avengers~

~blood and water~

Penny wasn't Steve's daughter. Not really.

On paper, she was his and Tony's foster daughter, but that was more of in name only than it was anything else. Besides Clint, none of the other Avengers were parents, and Tony had promised Penny when they'd done the paperwork after hearing that she would've been put into the system otherwise (and it didn't need to be said about how bad that would be for her, considering she was an omega, even though she was enhanced) that they wouldn't act like her parents if she didn't want them to. Mentors, yes, that was true for all of the Avengers besides the twins, who were only three years older than her. But not parents. And Penny had taken him up on that offer.

Besides Steve, she was the only other omega on the team. All the others were either alphas, betas, or theta in the case of Natasha, but the Avengers only had two omegas. Steve felt a sense of camaraderie with her because of it. When she was getting ready for her first heat since moving in with all of them, he hung out in the doorway to her room in his and Tony's penthouse at the Tower, because that was where the social worker had wanted her to stay and she'd said she was fine with it. He hovered there, watched her spread out the heated blanket on her bed even though she'd told him and Tony that her heat probably wasn't going to start until late that night. "Are you sure you don't need anything?"

Penny just about jumped out of her skin, her eyes going wide as she looked up at him. "Steve!" she squeaked. She still said his name like she wasn't sure of how to say it, but it was a lot of progress from how she'd been insistent on calling him "Mr. Rogers" when they'd met for the first time after Germany. After he'd dropped that passenger boarding bridge on her. She looked over at her dresser nervously, where the rest of her supplies were. "Yeah, um, I've got everything that I need. Thanks, though."

"If you wind up realizing you don't or you need me for whatever reason, just call for me or tell FRIDAY that I need to come in," he offered, hoping that he wasn't stepping over any boundaries. "Because I will, I promise."

She gave him a smile. He couldn't help but notice how shaky it was. "I won't. But thanks, Steve."

(And she was right. She didn't call on him or Tony for her entire heat, not once. She did have to restock up on food twice, they could tell by her scent in the kitchen, still there even hours after her brief stay in the room, but she did it at a time when they were both gone from the penthouse. It made his heart hurt that she thought she had to that on her own, because it felt like it meant she wasn't comfortable enough to ask for his help as a familial omega, even though he wasn't her parent. But again, he didn't want to intrude on her boundaries. He wanted her to feel safe here, whatever way that entailed.)

Steve wasn't her omither – she hadn't even had an omither, as her male parent had been an alpha and her female parent a theta, thus her father and mother/themither – and yet he couldn't help but notice the way she acted around the rest of the Avengers, even Tony. The omegan eye was always observant, as his own mother had used to say, and it seemed in this case even more observant than Clint's and Natasha's despite them being super spies. He was the only one to see how tense she was around, with the exception of Bucky, all of the alphas on the team, including Tony. Her shoulders were always slightly raised, her spine straight, as if she was preparing for a fight at a moment's notice. Even around the people she was at ease with like him, the twins, and her friends Ned and Michelle, who she brought over a few times (once for a school project, and the two times after that simply to hang out), there was always a guarded look in her hazel eyes. Like she was prepared for something bad to happen at the drop of a hat.

He also couldn't help but worry about her on the days and nights she went out on patrol, which was most of them. He knew that she could more than hold her own as Spider-Girl, the whole incident with the Vulture was proof of that, and yet she had a blatant disregard for her own wellbeing that he knew alarmed everyone else on the team, although none of them would admit to it in her vicinity. At least one night a week, she was coming back to the Tower more bruised up than she should've been, or with a nasty slice or stab wound that Steve had to break out the first aid kit for even with her enhanced healing factor, so much greater than his own, because he refused to let her go to bed without some sort of medical attention.

"Penny," he said one of those times as he applied disinfectant to a deep gouge on her upper left arm. If she was him or anyone else on the team, he would've insisted on taking her to MedBay to get stitches, but they'd learned the hard way that if the stitches were in her skin too long her body would heal around them, which would make for a nasty removal. It was simply better for her to go without unless the situation truly required them. "You've got to be more careful."

The younger omega shrugged, not even wincing at the pain it had to have caused. "I am careful."

He gave her a look.

"What?" Penny yelped. "I am!"

Steve worried, too, about how much she ate. She had a greater metabolism than even he did, and yet it seemed like every other day she was picking at one of her meals, if not multiple. He would've been willing to blame it on his and Tony's cooking skills, because neither of them were that great of cooks, but she'd informed both of them that they were much better at it than her aunt and uncle had ever been, and she'd lived with them for most of her life. Plus, a lot of the meals they ate were takeout and/or eaten with the rest of the team, so it wasn't like his and his husband's lack of cooking capabilities were entirely to blame.

He knew that Tony felt the same way that he did, despite him not noticing everything that Steve did, if not more so. Hell, even before Penny had called them crying in the middle of the night to tell them that her aunt had been killed in a car accident, Tony had been referring to her as "his kid." His face was always full of love and pride whenever he spoke about her, and even the times that he got angry at her, the ones relating to the Vulture incident or not, he could never stay that way for very long.

But, Steve and Tony weren't her parents. Penny didn't want them to be. They were her foster parents on paper, but that wasn't how she actually saw them. Steve knew this. He accepted it.

Four months after the paperwork had been signed and she'd been allowed to move in with them, and three months after her first heat in the Tower and a couple days after her second one, Steve woke up in the middle of the night – well, not the middle, more like three-thirty in the morning, but that was semantics. This wasn't uncommon for him; he'd gotten used to sleeping in shifts during the war, and after to having to often find his alpha working down in the labs and persuade him to come or come back to bed. Tony was sleeping next to him on this night in particular, his face relaxed in that way it only was when he was asleep. Steve smiled at him softly, ghosting a finger along his hair. He loved his husband.

He got out of bed, knowing he was going to need to walk around and maybe get a glass of water from the kitchen before he went back to bed. He ran a hand through his hair, then opened the door to their bedroom before he started walking down the hall towards the main room. The floor didn't creak beneath his feet; that was one thing he didn't like about the Tower and the Compound, though only Rhodey and Maria stayed there often. He liked the subtle noises that floorboards would make; they were comforting, reminding him a lot of like back in the '20s, '30s, and '40s, when building materials were a lot different.

He paused in front of the closed door to Penny's room when he reached it, as he always did when he woke up in the middle of the night. She was a quiet sleeper; usually, all he ever heard from her room after she fell asleep was her steady breathing and her heartbeat, and tonight was no different in those regards. Though her breathing was a little quicker than what he was used to, she didn't seem to be in any distress.

After a few moments of listening to her, straining his ears to do so, he closed his eyes briefly, opened them, and then he began to move on.

But then, after taking only three steps, he stopped in his tracks as Penny abruptly let out a whimper.

He retraced those three steps, going back to stand in front of her door. As he listened, she kept on whimpering, her heart beginning to beat faster. He wasn't quite sure of what to do. He knew that she had to have nightmares, because all of them did due to this line of work that they'd chosen, but he'd never caught her beginning to have or in the midst of one before. He and Tony had never asked her before how she'd want them to respond to her having a nightmare in the same that they had each other when they'd first gotten together. In retrospect, that probably hadn't been one of their brightest ideas. They should've asked her about it, now that she was living with them.

He hesitated, torn between leaving her be and going off to get his water or opening the door to check on her. With how wary and guarded she was all the time, he wasn't sure if she would appreciate him doing the latter. She might even get angry at him for the intrusion.

His decision was soon made for him. Penny's whimpers not only became louder, her heart not only beat faster and faster, but he also heard her start to moan, "Skip...Skip, no...stop, please...you're hurting me..."

Whatever nightmare she was having, he did not want her to be having it anymore.

Steve opened the door and shut it behind him quietly, so that he didn't startle her and that Tony wouldn't wake up and decide to come check on them. It was nothing against his husband, but he knew without a doubt that this was not going to be the kind of situation an alpha should stumble upon. Not if what he realized he had been suspecting for a while now was correct, as much as it pained him to think about.

Penny was now tossing and turning in her bed, her eyebrows furrowed and a deep frown set in her face. She shook her head wildly. "Skip," she said again, her voice becoming louder. "Stop...stop...!"

Steve made his way over to her bed. He crouched down as his instincts instructed him to, so when she woke up, he would be eye-level with her instead of standing over her. As gently as possible, he shook her shoulder. "Penny," he whispered. "Come on, Penny. Wake up."

That was all that it took. All at once, Penny woke up. She looked around the room wildly, not immediately noticing him. When she finally did, however, her glassy hazel eyes went wide, and she sat up and backed away until her head hit the headboard of her bed with a smack! "Skip," she said, and he realized that, though she was awake and looking at him, she wasn't looking at him, if you knew what he meant. "No, no, no...you're not real, I know you're not real..."

He didn't reach out to her, even though a part of him so desperately wanted to. "Penny," he said softly. "It's me, Steve."

But for some reason, rather than her snapping out of it and recognizing him, that just seemed to make it all the more worse. "No!" she cried out, so loud Tony might've been able to hear her anyways in spite of Steve's actions and the sound-proofed walls of the penthouse. She shook her head again, squeezing her eyes shut and clamping her hands over her ears. "You're not real! You're not real! This is a dream!"

Desperately, Steve tried to figure out what to do. He'd never been in this situation before. He knew that Wanda had had a...similar experience to what Penny apparently had had, but she always dealt with those issues in private on her bad days, only seeking Pietro out for company. And yeah, he'd helped more than a few shell-shocked omegas and beta women during the war, but he'd only helped them get to safety. He hadn't helped them through the aftermath. Not like this.

As Penny began to hyperventilate, rocking back and forth, however, one option came to mind. It made him swallow, because he wasn't sure if it was going to work, because she didn't see him in that way, but it was a better idea than any of the alternatives that he had.

"Penny," he spoke softly again, wincing at how she jerked at the sound of his voice. She had enhanced hearing, so of course she could hear him over her own words, and through her hands over her ears. "Penny, it's okay. Skip's gone; he's not coming back. I'm not him. I'm...I'm your omi."

He was surprised at how fast it worked. At the mention of the name for a male omega parent, Penny stopped rocking. She froze, and then her hazel eyes opened. She looked at him through her tears. "O – Omi?" she whispered.

He nodded, reaching over to her nightstand to turn on its table lamp. The action made her flinch, until the light played out against his features. She relaxed, seeing the confirmation that it really was him, and not this Skip person she'd thought him to be. "Yeah, Penny, it's me," Steve soothed her anyways. "You're safe. I'm the only one here, don't worry."

Steve was expecting her to retreat in on herself, as she always did whenever around anyone else, even her friends. It made perfect sense to him now, why she acted that way. But Penny must've ben rubbed raw from her nightmare more than he'd thought; instead of doing what he was expecting and trying to push him away, she broke down further into tears, wrapping her arms around her legs, which she'd pulled up to her chest. "Omi..." she sobbed.

His omega instincts kicked more into gear than they had before, the urge to protect and comfort the younger omega, his daughter (even though she wasn't really his daughter), becoming overbearing. "Baby," he breathed, his heart doing what felt like spasms. "Can I come up there?"

When she shakily nodded, he climbed up onto the bed. It was a queen-sized bed, because Penny had downright refused the king when Tony had asked if she'd want that instead of the queen her bedroom had come with, so it was a bit of a tighter fit than it would've been otherwise between the two of them. But Penny didn't care about that; like a sponge or a barnacle, she attached herself to his side, burrowing her face into his torso, and his nightshirt quickly became wet with her tears.

He reached down to pet her hair, but when that made her freeze once more, he settled on rubbing her back. This seemed to be okay; she began to relax under his touch, the muscles in her shoulders slowly losing their tension. "It's okay," he repeated quietly, his voice barely there. He knew she could hear him regardless. "Don't worry, Penny. I'm here...I'm here..."

He spoke sweet nothings to her, over and over and over again. He wasn't really sure of what he was saying himself, the words falling out of his mouth in a litany, but they seemed to do the trick. Eventually, her sobs devolved back into whimpers. She became boneless, a little omega snuggled against him, both in terms of age and size. She quite honestly reminded him of a baby bird; stronger than one might have expected, but fragile nevertheless, thin and with light bones from both her anatomical changes and what he could only assume was her doing a hell of a job at hiding her malnutrition. Neither he nor Tony had noticed. They'd known she was lighter, yes, but she hadn't wanted to do a thorough examination with Dr. Cho or Bruce and they hadn't been willing to do the "when push comes to shove" routine with her on that yet. It now made perfect sense why she was so reluctant...

When Penny was ready, she peeked up at him, wiping at her eyes. She was too exhausted to push herself away, which was what he had a feeling she would've done had she not been so tired. "Omi...Steve," she corrected herself, but her nose subtly wrinkled, like she wasn't sure if she liked how his name sounded coming from her mouth right now. "Steve. 'M sorry I woke you."

"Hey, none of that now," Steve told her. "Like I said, it's okay. You're okay. You're in your bedroom at the Tower."

"I know," was her weak response.

He waited for her to say something else, a brief quiet settling once more over them. But when she didn't, he had to ask, though he had a feeling he already knew the answer, "Do you want me to go get you a glass of water, or – ?"

"No! Please don't go!" she cried, true to his expectations. Then, as if she thought that sounded too desperate, she wilted, adding on, "I – I mean, can you stay for just...a few more minutes? I...I don't want to be alone."

"Of course." He gave her back another pat. "I'm not going anywhere until you want me to. Even if you want me to stay the entire night."

Her face reddened. "You don't have to do that...just a few more minutes," she mumbled. "He just...he always comes back after a heat. Always. May would sleep with me for the rest of the night...if she wasn't on shift...but..." Her bottom lip trembled. She didn't need to finish that train of thought out loud for him to know how it ended.

"May's not here anymore."

"I'm fine with staying here for the rest of the night, Penny," he assured her. "You're not a burden." You never have been."And you don't have to talk about him, either. You don't have to explain."

She sniffled. "I know," she said again. Then: "...I want you stay."

"Then I will," he promised. "When you wake up in the morning, I'll still be here."

"Th – thanks, Omi," she whispered.

Though it made his heart flutter inside his chest, he said nothing about her reverting back to the name.

At his suggestion, which Penny agreed to, FRIDAY started to play an episode of Milo Murphy's Law, an offshoot of another show, Phineas and Ferb, both of which Penny had said she'd adored ever since she was a little kid, on the TV in her room with low brightness and volume in order to help calm down the younger omega some more. Between the show and Steve rubbing and patting her back, the attempt was successful. Twenty-five minutes later, as the second episode automatically began to play, Penny slipped off into sleep once more.

Steve did not. His mind was a whir with too many thoughts for him to fall back asleep easily. He knew that in the morning, which was really just later this morning, he was going to have to talk with Tony...whether or not Penny would be included in that conversation, that was up to her. He wouldn't reveal what she had revealed to him about her trauma, not that there was much that she had revealed to him in the first place, but he and his husband were going to have a talk, because he realized now that some things were going to need to change in order for Penny to feel comfortable here. More than that, they also needed to get her seen by Helen and/or Bruce, and come up with a solution to her lack of eating. With how he could feel it had already affected her, they couldn't let it continue on any longer.

But, those were things that he knew he could worry about later, as hard as it was for him to. For now, he tried to focus his thoughts on the one good thing that had come out of tonight:

Penny wasn't his daughter, and yet, as far as she was concerned...she kind of already was.

Word Count: 3,647