Lorne only knew of the Camelot crew through Freya. He had spoken to Gwaine and Morgana a few times, to Merlin a little less than that - he wouldn't go so far as to say he knew them. However, he did know the hero types. And the over-protective ones: the ones who would do about anything for family. While he wouldn't place Morgana in the first, he could glean enough from her text and the times that he had met her that she was very much the second. And since this was involving Gwaine, and anyone with eyes could see that Merlin was definitely the first with a strong bit of the second, he knew he wasn't wrong in assuming that the young warlock would be accompanying his seer friend to save the knight. Oh yeah, he knew just how odd that sounded (and to think his mother had been adamant that he wouldn't be around anything worth seeing if he'd taken on music as a way of life).
He also knew that Freya would be worrying herself sick over all of them, Merlin especially. He might not know her family but he did know her. He and his roommate got on splendidly for all of her mousy ways (ha! .. no pun intended) and all of his more over-the-top-singing-show tunes-in-the-shower. Which was why he was gently knocking on her door, "Freya? Sweetie?" He called, letting that be his announcement before pushing into his room. "Now if this isn't just a perfect picture of Girl Worrying Herself Sick, then I don't know what is."