Pulling Regulus close again when he settled back against him, Remus raised an eyebrow at the questions of why. "Why did I care? Regulus, I love you." He cupped the other man's cheek gently with one hand. "That didn't stop just because we weren't talking. I didn't stop wishing for a forever with you because in the moment we weren't speaking. I never once thought we wouldn't be speaking again. I have known since that first afternoon in the library that this was what I wanted, that I want to make a home with you, a life with you."
Resting his cheek against Regulus' head, he took a breath before laying out everything he'd been looking into. "Don't laugh, but the research actually started out as a way of learning how to communicate better. I went back to the source, as it were, and started looking up everything I could find on the friendship between Gryffindor and Slytherin. They were friends before the argument that sent Slytherin away from the school. I thought maybe it would give me some ideas.
"In any case, I started looking into historical precedents for the extra-marital lovers idea and the legalities for two men having children, legitimacy, etc. equally. That was how I wound up getting more information from James about those Muggle methods he'd talked about. Legally, it's still a grey area. But, you have very ambitious brother-in-law and honestly, he and his husband really need to stop talking to us about having children and talking to each other. James intends to push the legal issue so that there won't be any question about the legitimacy of any children they have. Muggle laws apparently already have processes in place that would essentially create a contract between the biological mother and the fathers in which she gives up all rights to the children and the non-biological father can then legally adopt them as his own. James wants to push for a similar change in our laws for his and Sirius' children."
And that much, Remus had no doubts would actually happen. James Sirius Potter was one very determined young man with a wealth of social and political clout at his disposal.
"He also happened to mention that magical research of the nature that would be required to craft a Magical way of mimicking the Muggle methods he used is a particular interest of the same Healer who worked on the curse affecting the boys and cured Harry after Lily Luna attacked him, Nott. My father may have been a Healer, but I don't have his knowledge and we're going to need someone with medical knowledge beyond what either of us have."
Chuckling, he kissed Regulus' temple. "Have I lost you in all that, yet?"
Rolling his eyes, he grinned back. "I'm sure I could find the motivation needed to remove all evidence in this case."