Hmm. Terezi's major problem seems to be problems with Heart, both with herself and others. It seems to be a Seer trait, with them falling into trouble due to flirting with the opposite aspect for most of the session and an obsession with their aspect to the exclusion of all else (resulting in them falling wholly into the grasp of their opposite). Take Rose, for example, who I'd argue struggles with Void most.
She enters the game, then immediately begins to rely on Void to try and shed some Light on the matter of their session. This drive envelops and consumes her, causing her to avoid the others and normal contact in order to hunt for just a little more information, to the exclusion of all else. When she eventually finds out that her mother died, she blames herself for going on that tunnel-visioned drive for Light, and in the heat of the moment, enters wholly into Voids domain in the form of the Bloodfester Throes. She then casts aside her drive for Light ("Tired of reading. Gotta find Jack.") as she hunts for Jack, still Grimdark. She then dies as a result, and emerges as the Seer of Light after her suicide mission. She still does struggle with Void (in the form of alcohol this time) until after the RetJohn, when Vriska forces her to stop.
Terezi is much the same. In her session, she constantly flirted (pun intended) with Heart (in the form of romance), with Karkat. However, her troubles didn't truly begin until they went onto the meteor. There, she became obsessed with Justice, wholemindedly and completely obsessed, to the point where she began to shirk logic. This came to a climax with her encounter with Vriska, and she executed Justice. However, her guilt ended up leading her to fall into hate -Heart yet again- with Gamzee, which we can all agree was an utter abusive disaster that led her to ruin. Death again held salvation for a Seer, in the form of the scarf that held John's instructions. It protected post-Retjohn Terezi from the worst of her problems with Heart, but she, too, is again troubled by Heart even after death and rebirth, which leads up to [S]Terezi:Remem8er.