Showrunner Matt Hastings explained that Hyland showed him a photo of her Halloween costume last year — which just so happened to be a fairy costume — and that pretty much cemented her in his mind as the Seelie Queen.
Dominic Sherwood was thrilled to see Hyland take on this character too, especially since it's a role so different from the one she's used to playing. "It's really nice to see Sarah delve so deep into a character for the first time in almost 10 years because she's been on [Modern Family] for such a long time. It's been the same character, so for the first time she's got to really stray away from that and play someone very different."
Shadowhunters airs Mondays at 8/7c on Freeform.