User blog comment:Crimson and Darkness/Volume 24 discussion blog/@comment-177.134.149.241-20180112223737/@comment-2601:8C:601:5692:70F4:6327:4182:E9AD-20180117034731

You know, I can't help but wonder why people bother asking questions that can't truly be answered yet, as that part of the story hasn't even been written yet. The only one who could answer that is Ishibumi, and he's not going to reveal that yet. Our best educated guesses only come from him revealing who will be focused on in future volumes (and from existing material like EX), but, while highly likely, there's no guarantee that Issei will make a proposal in a given volume (or even before the end of the series). And you're forgetting Elmenhilde (one of Issei's confirmed wives from EX) and Kunou (whose intentions are well known already), both of whom are way higher on the list of potential wives than Roygun, who isn't even officially a harem member yet. Also, IMO, neither Tiamat nor Gabriel NOR Grayfia for all those shippers out there (Sirzechs IS NOT DEAD and Issei respects him too much to NTR him). I just can't see it happening. At the very least, I don't see it happening before Issei's graduation, if Gabby and Tia get added it'll only be seen after a time-skip at the end of the series or something like that.

About Vidar...it's like what Crimson and Darkness said. He's also Vali's adoptive older brother. Rose's relationship with Ise is likely known but the Norse higher-ups simply don't care as they're only interested in her fame, and the chance to expand Norse influence in the Alliance and such. Also, I personally use the form Viðarr for his name, but if you don't feel like using the "ð", I'd still recommend at least using Vidarr instead, as it might help people to not confuse it with similar-sounding names like Videl (which I've seen) or Vader. :P