Unlike Arya, when Sansa is tired of her life-tired of simpering girls, exhausted with endless gossip and abusive boyfriends, she escapes leaves home, enrolls in law school and realizes she enjoys it. Sansa passes the bar, after far too many sleepless nights and black coffees, before realizing she has nowhere to go. It's either working for the Tyrell's firm-Joffrey is always there because of Margaery- or Petyr. (He is old friends with mother, but his reputation is well known, and she'd rather not risk it.)
Luckily, she meets Joffrey's uncle. She accepts the rather surprising job offer; rude bluntness mixed with wit is a refreshing change from how everyone's treated her for the past few years. They set up an office-financed by Tyrion's uncle and the trust fund Sansa has never used-and she starts to feel content. Of course, that's before their first case, when she learns precisely why he's been without a job for the last year.
It's going perfectly, until Viserys Targaryen makes a very...pointed comment about Tyrion's height. The next thing Sansa knows, Judge Arryn is yelling at her partner to stop accusing Viserys of incest and relations with horses. (Tyrion follows that by calling Arryn's wife "a frigid bitch.") Sansa steps forward, nerves humming in terrifying anxiety. She takes over as quickly as she can, somehow managing to argue against Viserys and win the case while mollifying Judge Arryn.
It's a fantastic rush, and Sansa is certain she already loves her job.
She looks over at her idiotic partner, trying and failing to scowl at his faintly smug smile.
Tyrion reaches to open the courthouse door and steps aside for her-the only time she's ever seen the man act like a gentleman-and follows Sansa out, whistling The Rains of Castamere.