Hawkeye was sent on a mission to kill her but decided to bring her in
Nick Fury saw her potential on a mission and offered her a job
The Red Room sold her to S.H.I.E.L.D thinking she would work for HYDRA
She broke into S.H.I.E.L.D's headquarters but Hawkeye captured her
Ada Albano hasn't written a bio just yet, but if they had... it would appear here.