Disclaimer: The stuff's not mine, sadly, or there would have been much more naked Erik and Charles. Together. In the shower.
Erik paused as he left the bathroom, eyes moving from the door to the study (his intended destination, where his clothes were and he needed to put them on if he was to head back to his room) to the bed (far too expensively decorated and big for his tastes, but the figure in it normally made up for that by clinging so tightly around him it was a wonder he could breathe still). He had a rule against getting in a bed occupied by a sleeping person. Actually he had a lot of rules, and that was one of the fairly newer ones.
There was the one about only ever spending one night having sex with a person. Sprung up after he had made the mistake of going back to a woman a few months later. She had been more than welcoming, and once they were done declared that she loved him. He wasn't sure if he had ever made a faster retreat. Charles had broken that rule for him fairly quickly, but that was just a matter of convenience. They had to be around each other for a time. They were both attractive and amazing in bed. They were both safe, free to use powers around each other, not have to worry about a slip-up. It was smart, so that rule didn't apply here.
There was the rule against homes. Sex would be had in motels, hotels, alleys, cars, even once still in the bar but it was That kind of place. Homes were too comfortable, they suggested getting lost in worn in blankets, holding each other all night and staying for breakfast. Homes were dangerous. The Xavier mansion, however, was a necessary exception. It was a safehouse, a place for the team to remain safe while they finished hunting down Shaw, so that rule didn't really apply here either.
There was, on that note, a rule against teams. Other people were a mess he had to look out for. They did nothing but get in the way, ask questions, meddle in affairs that had nothing to do with them. They were never worth the trouble. This team, however... They could learn to take care of themselves. They all had abilities, and for the most part they had pasts that kept them from being too nosy about his. No one wanted to run the risk of their own history being questioned in retaliation. This team wouldn't distract him from his goals with their stupidity, so that rule could be set aside.
There was the rule against family. The hardest learned rule of all, born through the bullet that pierced his Mama's skull and the fire that burned his daughter and the beautiful gypsy who had taken his heart and whatever trace of humanity remained with her when she ran from him. The children here could become Charles' family, that was fine by him. He would have no part in any of the Family Activities the younger man insisted on arranging. Even if he once or twice made the mistake in his mind of referring to them as 'Our children', it meant nothing. He had no family. That rule remained in place.
There was the rule against possessions of any kind. He carried the coin with him wherever he went to keep him from being caught unaware by Schmidt. He had a briefcase to use whenever he had things to transport. Nothing else was his, not even the clothes he wore. Not really. Bought, worn maybe once or twice, then discarded before he left town. No extra baggage, nothing to leave behind when he left like he always did. And then the idiotic little Professor had to declare that he belonged to Erik. He was Erik's. A responsibility and attachment (another thing he had a rule against) he never wanted. But the telepath seemed to have his mind made up on the subject, no matter how often Erik told him it was a bad idea, he would get hurt, and there really was no way to change that stubborn man's mind. Like it or not it seemed Erik had ended up with a possession of his very own, and that rule was broken.
There was the rule about keeping his own secrets, but that one had been broken the moment Charles dove into the ocean (and his mind). Everything had been left open and exposed, and if he was honest there were times he completely forgot that Charles had spent days getting rid of the memories. Times when a flash of his history crossed his mind and he couldn't think why it seemed like the telepath was shocked by that. He had seen it all before. And, in complete honesty, there was a part of him that would rather just be able to lay it all out and open again. But Charles didn't deserve to have to see everything Erik had been through. He had seen the effect that those memories had on the other man, and how hard he had worked to remove them from his own mind, so Erik wouldn't do him the dishonor of forcing them back on him. He would try his best to remember that his past was his own, and to keep that rule in place.
A soft sound from the bed snapped his attention back to it, to the body laying curled up on it, suddenly looking so fragile and young with an expression of pain flickering over his face. Nightmare, most likely. Hadn't Charles come to his room just nights before because Alex's nightmares were keeping him up? They needed the Professor rested to train the children and keep an eye on the house. If that only happened when he was with Erik it was practical that Erik stayed.
Another rule broken as he slipped under the covers, arms wrapping around the telepath and pulling him close. A soft humming filled his mind, chasing the nightmares away until he felt the smaller body relax and curl against him.
There was still perhaps the most important rule, the rule to trust his instincts. If they said to get out of a situation, he listened. If they told him a person was dangerous, too dangerous for even him, he treaded carefully. If they told him he was getting too close, too near being attached, he fled. And for the first time in a long time, he was ignoring them completely. Everything was screaming for him to leave, find Shaw on his own, get out before it was too late. But Erik knew the truth.
Settled on the bed with His Charles sleeping soundly half on top of him, gentle brushes of contentment and affection lapping at the edges of his mind like some emotion always was, running over plans for what to do with the training of their children tomorrow as he temporarily held back sleep, it was already far too late to get out of this without getting hurt. And he would take whatever wounds he got for just another minute of this.