Fear did clutch at Remus' heart. He'd numbed himself (mostly) back in his time, or at least he'd convinced himself that he had. Sometimes he still had breakdowns, moments when all he could do was cry over the loss of everyone he'd held so dear to him and being unable to be near the one living person he had any connection to those lost souls (Harry) to find even a shred of comfort. It was a lot. But he'd been trying his hardest to keep a grip on himself and maintain some semblance of an existence for the sole purpose of seeking out Harry when he was older to tell him anything he wished to know, and his continued hope that something would prove Sirius innocent and released from prison. In this weird little town, he'd been gifted with the latter. Gifted perhaps was a strong word because it meant the betrayal came from someone else he'd once loved and trusted, but at least they knew the truth.
Now, he was scared. Even though he'd been coping with the pain of loss at home as much as he could, the thought of having Sirius back -- finally, in a way that they'd always been meant to be -- only to lose him by means of the Door or otherwise, was something that terrified him. Sirius, whom he loved endlessly and forever, could just vanish one day and there'd be nothing Remus could do about it. Or, Remus himself could go and it would leave Sirius alone. Sadly, he didn't know which would be the lesser of two evils. If they wound up going back home, then he'd want Sirius to be the one to go. Sirius had the power to change things, in theory, and he'd be going back to a time when he could make things right. He and Remus' past self could be together, and Sirius could stop things from getting so dark and bleak among their friends before the distrust happened. If Remus went back, however, he could hopefully get Sirius out of Azkaban once he found evidence of Peter's betrayal. But he didn't want Sirius to be here, alone.
He supposed that dwelling on it didn't do them any good. It was all out of their hands, at least as far as he knew. It just didn't feel right to sit back and hope for the best when they'd just lost James and a few others. Not to mention, thinking and overthinking were traits Remus had always possessed. Sirius was the only person who really could get his brain to shut the hell up and let him relax.
"That could be arranged. You might choke that way, though," he commented as he unwrapped the sweet, and held it to Sirius' lips.