▁going ▁to ▁work ▁out ", ▁j oking ▁that ▁" After ▁every ▁time ▁I ▁would ▁hope ▁that ▁they ▁would ▁call ▁and ▁also ▁hope ▁not ▁too   – ▁kind ▁of ▁like ▁when ▁I ▁used ▁to ▁be ▁single ." ▁However , ▁following ▁Washington ' s ▁departure ▁from ▁the ▁show , ▁H ahn ▁was ▁brought ▁back ▁as ▁a ▁main ▁character ▁in ▁the ▁show ' s ▁fourth ▁season , ▁replacing ▁Bur ke ▁as ▁Seattle ▁Grace ' s ▁Head ▁of ▁Card i oth or ac ic ▁S urg ery . ▁Smith ▁has ▁said ▁that ▁she ▁was ▁not ▁expecting ▁her ▁character ▁to ▁be ▁introduced ▁to ▁the ▁show ▁full - time , ▁as ▁she ▁" did n ' t ▁want ▁to ▁be ▁disappoint ed ▁if ▁it ▁didn ' t ▁happen ." ▁She ▁has ▁stated ▁that ▁a ▁dec iding ▁factor ▁in ▁her ▁return ▁was ▁the ▁opportunity ▁it ▁presented ▁to ▁explore ▁the ▁character ▁in ▁greater ▁depth , ▁explaining : ▁" When ▁I ▁work ▁on ▁something ▁that ▁has ▁a ▁beginning , ▁middle ▁and ▁end , ▁I ▁can ▁create ▁an ▁arc . ▁With ▁Dr . ▁H ahn , ▁I ▁need ▁to ▁figure ▁out ▁who ▁she ▁is ". ▁Research ing ▁the ▁role , ▁Smith ▁watched ▁a ▁heart ▁surg ery ▁performed , ▁and ▁l ia ised ▁with ▁the ▁surg ical ▁n urs es ▁employed ▁by ▁Grey ' s ▁An atom y ▁produ cers ▁to ▁maintain ▁real ism ▁in ▁the ▁show ' s ▁operating ▁room . ▁She ▁dub bed ▁this ▁research ▁stress ful , ▁stating ▁that ▁" I ▁got ▁very ▁ne uro t ic ▁about ▁the ▁fact ▁that