▁Cat Co ▁after ▁Cat ▁Grant ▁leaves ▁the ▁company . ▁ ▁Ch y ler ▁Le igh ▁as ▁Alex ▁Dan vers : ▁K ara ' s ▁human ▁adopt ive ▁sister . ▁She ▁is ▁a ▁phys ician , ▁scient ist , ▁and ▁government ▁agent ▁who ▁serves ▁as ▁H ank ▁H ens h aw ' s ▁right - hand ▁at ▁the ▁DE O . ▁Having ▁been ▁extens ively ▁trained ▁in ▁combat ▁by ▁H ens h aw , ▁Alex ▁in ▁turn ▁provides ▁rig orous ▁training ▁to ▁K ara ▁in ▁order ▁to ▁decrease ▁her ▁over - re liance ▁on ▁her ▁powers . ▁She ▁and ▁K ara ▁grow ▁susp icious ▁of ▁the ▁DE O ▁upon ▁learning ▁that ▁their ▁missing ▁father ▁was ▁forced ▁to ▁work ▁there ▁in ▁order ▁to ▁protect ▁K ara , ▁but ▁Alex ▁ultimately ▁lear ns ▁that ▁H ens h aw ▁is ▁really ▁the ▁Mart ian ▁surv iv or ▁J ' onn ▁J ' on zz ▁in ▁dis gu ise , ▁whom ▁her ▁late ▁father ▁had ▁res cu ed ▁before ▁his ▁and ▁the ▁real ▁H ens h aw ' s ▁apparent ▁death s . ▁In ▁season ▁two , ▁Alex ▁lear ns ▁that ▁her ▁father ▁is ▁alive ▁and ▁searches ▁for ▁him . ▁She ▁also ▁meets ▁and ▁be fri ends ▁police ▁detect ive ▁Mag gie ▁S aw yer ▁and ▁begins ▁to ▁develop ▁feelings ▁for ▁her , ▁forcing ▁Alex ▁to ▁confront ▁her ▁sexual ity . ▁Jordan ▁Maz ar ati ▁and ▁Oliv ia ▁Nik kan en ▁port ray ▁a ▁young ▁Alex . ▁At ▁the ▁end ▁of ▁season ▁three , ▁Alex ▁becomes ▁the ▁new