A/N: Here is my first Erin/Aaron story. I guess it's my way of dealing with the season eight finale, since I like both Aaron/Erin and David/Erin and I hate the fact they killed her off. I might write a sequel to this. If you'd like that, leave me some ideas I can work with. Reviews are greatly appreciated, as is constructive criticism!

Disclaimer: I own nothing. Else, Erin Strauss would have had more screen time and she'd still be alive.

Chapter One

Man's nature is not essentially evil. Brute nature has been known to yield to the influence of love. You must never despair of human nature. Mahatma Gandhi.

As Erin Strauss made her way towards Aaron Hotchner's team, she was not surprised to see their mouths drop open. They hadn't been informed she was coming, after all. It had been a quick decision when word had reached her and her superiors their latest case involved a deaf six-year-old boy.

"Section Chief Strauss," Aaron said, bowing his head in respect. He seemed not at all fazed by her arrival. Erin was grateful for it; it would make it easier for the team to accept she was accompanying them.

"Agents," she greeted them, choosing to include everyone in one go. They knew she knew all their names, and it was faster like this; she'd barely made it to the airport in time as it was.

She gestured towards the jet. Another nod from Aaron was all it took for the team to begin moving. She waited until everyone was on board of the plane before boarding herself. Already, the thought of flying made her feel a little queasy.

As she had expected, everyone had already paired off. Morgan was sitting next to Blake. Reid was in front of Morgan, with JJ beside him. Aaron and David were sitting opposite each other. That meant she would have to sit next to one of them or separate herself entirely from the team. As she was there to help, that wouldn't do. Sighing inwardly, she sat down beside Aaron. David would only goad her and they would end up bickering. Aaron was the safer choice.

"Let's go over what we know, okay? We have a three quarter flight ahead, enough time to discuss some theories. First of all, the victims. There were a man and a woman, both killed by deep lacerations and stab wounds," Aaron began.

Erin listened closely. She only knew the basics, and she would need more to work with if she wanted to be an asset instead of a burden.

"There are no signs of hesitation. The lacerations are methodical, all equal in length and depth. The stab wounds follow the same pattern. They are also located around the major arteries, the victims would have bled out in less than three minutes. That indicates an in depth knowledge of anatomy," Reid spoke.

Erin nodded her agreement, even though she was unsure whether anyone was actually paying attention to her. Her eyes were focused on the folder Aaron was holding, on the picture the others were looking at as well. Suddenly, she noticed something.

"There are no injuries to the hands or wrists. It looks like they didn't defend themselves," she pointed out, unable to stop herself.

"That might have something to do with the boy the EMTs found at the crime scene. So far they haven't been able to get him to talk, so they can't be sure, but they think he might be the son. It's possible the UnSub used him as leverage," Blake said. Erin could feel everyone looking at her.

Looking at Aaron, she extended a hand. Wordlessly, he handed over his file. She flipped a few pages until she found the photograph of the boy. He was covered in blood, he was staring in the distance without seeing a thing. It broke her heart to see him like that. He reminded her so much of her own children when they were younger.

"That boy's the reason I'm here. I was contacted by my superiors. The EMTs discovered the boy is deaf. Since only agent Blake knows sign language, I was asked to come along, because I do to. That way agent Blake can help you while I tend to the boy," Erin explained her presence.

Reid's mouth was wide open. Blake blinked stupidly a few times. Morgan seemed to forget who she was for a second, quirking an eyebrow at her. Aaron was also surprised, but it appeared he was pleasantly surprised. David just grinned.

"There's a lot you don't know about her," he said, a disturbing twinkle in his eyes that made him seem years younger.

Erin groaned almost inaudibly. It was obvious she hadn't been mistaken when she though this case might hold more than a few hurdles for her. She quickly fixed David with the most intimidating stare she could muster. She failed miserably, but pretended not to noticed.

"Let's keep it that way a little longer. We should all take some rest or read the case files again. We'll have our work cut out for us when we arrive. There's a child that needs our help and a murdered we need to catch," she said.

The rest of the plane ride passed in almost utter silence. Not the tense kind, it was simply easier for everyone to focus on what they had in front of them. Aaron and she shared his file, which the man seemed at least relatively comfortable with. Relatively, because is posture was slightly less relaxed than usual.

Right before they landed, Garcia called to say the victims' names were Rebecca Eastwood and Simon Wells. She'd so far been unable to find any evidence their lives had ever intersected, but she was still looking. The boy, Arthur Combs, had been Rebecca's foster child for the last year.

When Erin finally stepped out of the plane, the cold wind blew her hair across her face. She quickly fished an elastic out of her pocket, pulling it into a lose pony tail. With her dark jeans and blouse she had to be looking rather different, but she didn't mind. She would be a lot more hands-on this time around, and these clothes were more comfortable than the skirts and dresses she usually wore to work.

"You should join us," David's voice suddenly sounded. "We'll be heading out to the crime scene while the others divide and visit the victims' parents."

Erin nodded, following David to the car. He ushered her onto the front seat while he slid into the back. It was so unlike David that she was about to ask him about his reasons, but she held back. There was no need to create an argument, so she wouldn't.

A quarter of an hour later they were greeted by the hustle and bustle of police cars, an ambulance and the medical examiner. In all the chaos, Erin immediately noticed one person was sitting unmoving. Arthur was sitting in a circle formed by two EMTs and three agents. His head was on his knees, his arms protectively around his head.

"Oh, for the love of god," she muttered, pushing open the card door as soon as Aaron stopped. She flashed her badge before anyone could even open their mouth and moved straight for the boy.

The EMTs and police officers were so focused on Arthur they didn't even hear her until she was right beside them and cleared her throat. Again, she showed her badge. There was no mistaking how displeased she was. But there was no malice in her behaviour, only concern for the boy.

"I want all of you gone. I bet there are more important things for you to do than harassing this boy. He's been through enough. He needs someone to comfort him and tell him everything will be alright in the end. Give me a few minutes with him. He might want to talk after that," she said.

Soon enough they were all gone. Erin could feel Aaron and David looking at her as she crouched down before the boy. She didn't pay any attention to them, though. Instead, she gently tapped the boy's left knee. When he didn't look up, she did it again. A smile graced her lips when Arthur kicked at her lightly, trying to spook her and make her leave.

She caught his foot and playfully tugged at it. This made Arthur lift his head. His eyes went wide when he saw a woman and not the police officers an EMTs that had been there before. She let go of his foot, shifting so she was a little closer to him. She slowly raised her hands.

"Hello, Arthur. My name is Erin. I'm with the FBI, that's how I know your name. I hear you don't want to talk to these people here. Why is that ?" she asked, signing the words while she spoke. She was a little slower than she'd have liked, but she was accurate.

Arthur's hand came up, moving gracefully and swift. They only want me to tell them who did this. But I don't know. They don't understand what I say. It makes them angry. I'm not important. Rebecca and that man are, he signed. Unshed tears shone in his eyes.

Erin squeezed his knee. She understood the officers had been angry with themselves for not being able to speak to the boy, and not with the boy himself. She got how that would make him feel unimportant.

"You are important, sweetheart. That's why we're here," Erin said, indicating David and Aaron as well as herself. "We're here to let you tell us what you know. To help you. Will you let us do that?" she asked.

As she spoke, Aaron walked over to them. He sank down next to her, so close their legs touched. Erin didn't feel the urge to pull away like she would have with anyone else. That had to do with the fact she liked Aaron a hell of a lot more than she should. Aaron had supported her when she had trouble in her marriage and when she went to rehab. And she had realized she would want him in her life for the good times as well as the bad.

Fortunately, she was dragged out of her thoughts by Arthur. Yes, I will let you help me. You seem nice. But only on one condition. You have to promise no one will hurt me anymore. I don't want to have to be afraid anymore, Arthur admitted. He worried his bottom lip as he signed.

As she told Aaron what the boy had said, she saw the anger she felt reflected in the man's eyes. He was probably reminded of his son Jack; Erin knew he loved that boy with all his heart. A by now very familiar warm feeling spread in her stomach as she watched him. Damn, woman, get a grip. The man doesn't love you. He isn't even attracted to you. Bury those feelings before you make a fool out of yourself, she sternly told herself.

"We promise we'll keep you safe, buddy," Aaron said, his fingers under the boy's chin to make sure he was looking at his lips. It seemed the boy at least had some lip-reading skills, as he smiled brilliantly.

The moment was broken, though, when Arthur yawned suddenly. A look at her watch told Erin he had good reason to: it was three in the morning. The boy probably hadn't slept much yet. And the bench he was on couldn't be very comfortable.

Making a decision, Erin rose and motioned for one of the EMTs. The man immediately approached her, his medicine bag still slung over his shoulder. It seemed he'd watching the boy discreetly, ready to come running to him at the first sign of trouble. That thought was comforting.

"Would it be okay for him to sleep a little? He's tired and he's been through a lot. But I don't know anything about his injuries, so…" she let her voice trail off, knowing it would convey her feelings well enough.

The EMT thought about that for a second. From the corner of her eye, Erin saw Arthur holding on to Aaron's hand as he attempted to get closer to her as well. Erin took his hand in hers, eliciting a smile and making his fidgeting stop.

"He doesn't seem to have any head injuries. We checked that out straight away. We can't be one hundred percent certain he doesn't have any bleedings until he gets a scan, though. Especially since we haven't been able to ask him anything. If he didn't bump his head or hurt it in any other way, I'd be willing to let him rest. As long as someone stays with him," the EMT added.

Erin sank down to Arthur's level again. She let go of his hand, bringing it up to communicate with him. She translated as soon as the boy answered her question. She noticed that her signing hadn't quite been as rusty as she'd feared.

"He says he didn't faint or hurt his head in any way. He was in another room when the fight happened. He didn't even know what was going on until he went to look for Rebecca to ask whether he could go to bed. It was then that the man pushed him against the wall, but his elbow was the only part of him to get hurt," she said, a sense of relief floating over her.

David approached them as the EMT told Erin it was fine for the boy to sleep a little. He did warn her that Arthur would probably wake up when he was carried to the ambulance, which would be shortly.

Arthur had apparently followed the exchange with rapt attention, because he immediately had a question for Erin. One that surprised her more than a little. Can I sleep on your lap? I'm a little cold, Arthur admitted shyly.

"Of course you can," she said, pulling the boy up. She shrugged out of her jacket as soon as he was comfortable and draped it over him. The cold bit harder than she'd expected, but she ignored it.

Rebecca always said I was too old to be on her lap. She never liked me. She only wanted me because she got money for me. That's what she said, Arthur signed. It made Erin shudder to hear that, and she quickly pressed a kiss to the boy's head.

Aaron walked away only to return a little later with a rather large blanket. He draped it over Erin and Arthur, tucking it in around them. The boy sighed contently and snuggled closer to Erin. She tightened her hold on him reflexively. Within minutes, his breathing slowed and evened out, indicating he was fast asleep.

"Thank you for the blanket," she said, smiling at Aaron. The man smiled back and settled beside her on the bench. David did the same on her other side.

For a second they sat in silence, ignoring the voices and commotion around them. But they all knew there was work to be done. So David eventually spoke up, dragging the other two back to the scene. Because they understood the need, they didn't complain.

"What have the two of you been able to find out so far? Anything that might be useful?" David asked, not even trying to hide the hopeful note to his voice.

Erin gave him a quick recap of what Arthur had told her. David took it in with a few nods and non-committal sounds. If she hadn't know the man as well as she did, she might have mistakenly thought he was not interested. But she knew he was only processing it all and that he was angry such a sweet child had been put through this.

"What about you? Have you got anything we can work with? I bet some fingerprints must have been lifted by now, and there has to be some indication as to where the man who did this entered," Aaron said as soon as Erin was done.

"Yeah. He entered through Rebecca's bedroom window. As far as I can tell Simon was in bed with her; the guest room wasn't being used. It looks like Simon was murdered first. I don't think Rebecca wouldn't have done what the UnSub asked for Arthur's sake, so it's likely he used Simon as leverage. Rebecca might have done what he asked, but he might have murdered him anyway because that was his endgame: murdering them both," David told them.

Erin mulled that over for a second. They had some information that could lead them to the murderer, but they would need more. It was a start, though.

"So he probably didn't know them personally. Else, he would have known they'd let him in. Or she would have, if she simply picked Simon up in a club or something. But he knew she was home. He must have followed her. Maybe he even stalked her for a while," she thought out loud.

David and Aaron let that sink in for a while. As they did, she absently stroked Arthur's back. It was strange to have the boy connect to her so easily, and at the same time it was a true honour. She just hoped she'd be able to help him as much as he seemed to think she could.

"He probably did stalk her. He probably wouldn't have acted this soon if she hadn't brought a man home, though. The pictures show uncontrolled rage and overkill. On both of them, which indicates jealousy and anger towards both of them. But we also have to take into account it might not have been about her. If it was, he could have easily waited to kill her until she was on her own. To spend time with her and try to get her to act out his fantasy. He doesn't seem to have done that. And this was not very organized: there are footsteps in the blood, the knife he used is still on the floor," Aaron pointed out.

There was no more time to think that over as the EMT Erin had motion over before reappeared. It was only now that Erin realized how tired the young man, whose name was Greg according to his badge, looked. He'd probably had a long and unpleasant night.

"We're ready to take him to the hospital. I already said you'll be going with him. My colleagues are fine with that," Greg said.

Erin smiled gratefully before standing up. As Greg had predicted, Arthur woke up because of the movement. He looked around frantically for a second. When his eyes focused on Erin, he calmed. And when he noticed Aaron, he extended a hand towards the man. Aaron took it without question, squeezing the boy's fingers lightly.

"Come on. I'm sure they won't mind you coming along as well. And if they do, well, they'll have to learn to live with it. Because I don't think that boy's letting go of either one of you anytime soon," Greg chuckled.

After making sure David would be fine, Erin and Aaron walked over to the ambulance. The ride was a short one; five minutes later they were in the emergency department and Arthur was being checked in.

Another ten minutes later they were in his room. The boy was sound asleep again, comforted by the fact Erin had told him Aaron and she weren't going anywhere. He was so at ease now that he didn't even wake up as the doctor looked him over.

"He doesn't have any really severe injuries. There's a lot of bruising, but that should heal within the next two weeks. Some of the bruising is older, which is why we've done the portable x-rays. Those show he's broken quite a few bones in the last year," doctor Marsh said as soon as he was done.

"Thank you, doctor. When will he be allowed to leave the hospital?" Erin asked, hoping for some good news.

"In a day or three, if you can guarantee he has someone to look after him. Else, we'll keep him here for a little longer until a foster family can be found," the doctor said.

Erin sat down on the chair beside Arthur's bed as soon as the doctor was gone. She sincerely hoped she would be able to find suitable accommodations for the child in such a short span of time. He would need her help in working through this, so that might prove a little tricky.

She was pulled from her thoughts when she heard Aaron move over the second chair and positioned it right next to hers. He was silent for a few seconds before he spoke, his hand laying close to Arthur's on the bed by then.

"You should show this caring side of you more often, you know. It's a good side," he said, his eyes fixed on the boy.

For once in her life, Erin had no smart remark to throw at him in return. Instead, she gaped at him with her mouth open for a whole minute straight before choosing to focus on Arthur.

But the question why Aaron would say something like that to her did not leave her mind. It was still there when she finally gave into sleep at six. As was Aaron himself.

It's a man's own mind, not his enemy of foe, that lures him to evil ways. Buddha.