Both Smallville and Jessica Jones featured characters who existed on the periphery of the superhero world but were never really a part of it: Lana Lang and Trish Walker. Lana was Clark Kent’s would-be love interest while Trish was Jessica Jones’ best friend and adopted sister. Over the course of each series, both characters went down dark paths that pulled them away from their heroes. However, while Lana eventually abandoned her quest for revenge on Lex Luthor, Trish pushed forward and fully embraced the violent Hellcat within by Jessica Jones' final season.
On a show with a singular protagonist, it can be easy for supporting characters to feel underdeveloped. This was certainly true for Lana Lang on Smallville. She had few internal motivations and her primary function was to be the object of affection for Clark, Lex and a significant percentage of everyone else. This lack of definition resulted in an incomplete version of what was meant to be a fully realized person. Jessica Jones' Trish Walker was the exact opposite.
Trish had an extensive and complicated backstory, interesting and specific relationships with the people around her and a strong, if monomaniacal, internal desire. Yet despite all this, there was a certain emptiness to Trish. Unlike Lana, whose characterization took a back seat to that of Clark, Lex and Erica Durance as Lois Lane, this wasn’t an accident. Trish was intentionally written to be an incomplete person.
An underdeveloped character and an incomplete person amount to much the same thing. Both Lana and Trish needed something they didn’t have to feel whole, and in each case, this need ended up pulling them in unsavory directions. After Lana’s ill-fated marriage to Lex, she became obsessed with exacting vengeance on the man who -- among other things -- dosed her with hormones to simulate a pregnancy as a means of trapping her in the relationship. Her anger was understandable, but as her plot expanded and caused more and more collateral damage, she got closer to crossing lines she couldn’t come back from.
As a former child star, Trish spent much of her life subject to the whims of directors, producers and, most notably, her mother. She faced abuse, fought addiction and struggled to find a life beyond the TV show that made her famous. Circumstance robbed her of control so it made sense that she would want to emulate her super-powered sister Jessica. Except once Trish gets powers of her own, she went too far and began killing people. For better or worse, Lana and Trish felt more actualized and complete once they began to stray from the straight and narrow. Agency is more interesting than passivity, and both Trish and Lana became three-dimensional when they made choices.
Agency was another place where the two characters differed. Faced with the opportunity to carry out her final act of revenge, Lana saw how far she’d gone and steps back from the ledge. Ultimately, she valued the relationships she stood to lose over the chance to destroy the man who wronged her. By and large, this made sense. Why would the writers of Smallville break with comics' long tradition of Lana Lang not being a supervillain? However, Lana embracing her dark side would have been a much stronger impetus for her final split with Clark than her skin absorbing so much Kryptonite radiation that she became a danger to him.
The writers of Jessica Jones took a different approach and allowed Trish -- also not a supervillain, historically speaking -- to follow her dark impulses to the end of the line. No amount of reasoning or pleading from Jessica or Malcolm Ducasse deterred Trish from metting out her brand of justice as she saw fit. Rather than remaining on the sidelines, pricking Jessica’s conscience or expressing envy over Jessica’s ability to make a difference, she took dark, violent action. This choice made her a murderer, put her at odds with Jessica and landed her in prison -- but it was her decision, her act of defiance against a lifetime of passivity.
Although they were both comic book adaptations, Smallville and Jessica Jones were very different shows, both tonally and thematically. As interesting as it may have been, Lana Lang was never going to make a heel turn. Smallville wasn’t that kind of show. Jessica Jones was, and because of that, Trish Walker got to go from sidekick to supervillain. For Jessica, that journey was tragic... but for Trish, it was a triumph of character growth.