Ok but listen...
What if the Suriel has offspring somewhere? I’m not saying it’s in Mor’s bloodline because her family/the Night Court seems hella into keeping their blood “pure” (I just threw up in my mouth) but I’m not ruling it out. The Shadows exist and they’re mixed in a way that seems out of the ordinary—at least to Amren (who said of them that High Lords will stick their cocks anywhere). But it doesn’t even have to be Mor’s line.
Suriel said it (he?) couldn’t read Feyre’s emotions because they were happening too fast. We know Shadowsingers hear and feel more than others, and we know Nesta can at least pick and choose between her own emotions similarly.
It honestly doesn’t have to be connected to anyone we know or have met. Just the idea. That a half Suriel is roaming around out there. Lookin half terrifying maybe. Enjoying long robes and chicken. Maybe by the seaside. Dropping truth bombs like dollar bills at a strip club. You know. Keepin’ it casual.