But (partly because Tosh is woefully underwritten) we get very little information on who she fancies. We see her pine after Owen and her relationship with Tommy in TTLM, but that doesn't strike me as enough information to establish her as definitively straight. Though, tbh, part of the reason I prefer to think of her as bi (other than fic purposes, obv) is that it makes GBG marginally less squicky if there's a chance she was attracted to Mary anyway.