At seventy, Charles would have been delighted to fuck Erik in his thirty-year-old body—had Erik retained his own seventy-year-old mind. That, however, was not what had occurred, more was the pity.
"You have to let me," said thirty-year-old Erik, who had spent the last several hours alternating between weeping with his head in Charles' lap and pacing stormily around Charles' office, destroying Charles' things (the latter of which was surprisingly par for the course, considering). Charles wasn't certain if this Erik was more upset that Shaw had been dead for forty years and that he couldn't remember killing him, or that he'd learned Charles had been paralyzed at Erik's own hand.
"You're not going to make up for the past forty years by sucking my cock," Charles said. And, frankly, young Erik's apparent assumption that it hadn't been sucked, and frequently, in the interim was rather insulting too. "In fact, I really would appreciate it if you'd shut up about it now. I thought we were past this. I liked being past this. You usually brood about it more quietly these days."
Young Erik continued to brood loudly for several more weeks. When he'd finally calmed down enough to stop thinking as much about how he should make it up to Charles, and to start thinking more about how muscular Charles' shoulders were, and how good bald-headedness looked on him, and all those other flattering things that seventy-year-old Erik thought about him on a regular basis whenever he wasn't too busy thinking about how Charles was a senile old fool who would bring them all to ruin—that was when Charles found an excuse to say, "You know, I can still do that thing with my tongue you like so much. And I've forty years of practice on you."
And so it was that he managed to get Erik into his bed. Erik at seventy was still beautiful, but Erik at thirty was a god, long and lean and lithe, eager and willing to fuck Charles' mouth for a grand total of about four minutes. (Old Erik had better stamina, so there was that.)
A few days later, Erik changed back. Charles was not the least bit surprised that it happened in bed, considering that he and young Erik had been spending most of their time in it. Charles had begun to feel a bit like a dirty old man, not that he'd been going to let that stop him.
"Welcome back, dear," Charles said, eye level to Erik's erect, wet dick, which he had enthusiastically been fucking Charles' mouth with several seconds ago. Charles wasn't sure how Erik's dick was still wet if it were now forty years older than it had been the last time it had been in Charles' mouth, but, well, nevermind. "I don't know where you've been, but I've missed you."
Not that he expected Erik to believe this once he discovered what had been going on. Erik was exactly the type to go into a jealous rage directed at his younger self. Even young Erik had gone into several sulky fits over knowing that his older self had slept with Charles more often. But, well, he had to try.