We have a few options for Influence Character.
Ian Malcolm is the official storyform's pick, and he seems like a logical choice. There's a reason his dialogue is so often cited. All his speeches about chaos and nature finding a way feel really important to the story. Honestly, though, I think he's only in the OS. He actually has very little interaction with Grant--none at all in the second half, and it never seems like Grant is dwelling on what Malclom has said. Once they're separated, the only time Grant gives Malcolm any thought at all is when he finds the eggs.
Hammond is a possibility; he benefits from probably being the best developed character in the story. Despite that, I think he's also only in the OS. I believe his development is largely due to his being the protagonist. He's the one driving the pursuit of opening the park and cloning the dinosaurs, and he's often asking the others to consider how the park is still salvageable.
My personal pick for IC is the dinosaurs themselves. I always feel like I'm out on a limb when I start considering non-humans as characters, especially something as important as IC, but I think there's a strong case here. Nothing in the story has as big an impact on Grant as his interactions with living, breathing dinosaurs. The most emotional core of the movie is structured around these interactions. He's completely awestruck when he sees the brachiosaurs. He lies across the chest of the triceratops, and when he recounts how the trike was his favorite dinosaur as a kid, its probably the most emotional he gets in the entire story, barring the times he's scared to death he's about to get eaten. He's completely drawn to them. He even lingers, perhaps imprudently, to observe the T-Rex feed.
For Grant, the dinosaurs represent both the opportunity to prove his theories and an existential threat to his way of life. Being trapped in the park with them forces him into a parental role with the kids. All these things pressure Grant to change, to evolve or die out. Grant himself is a metaphorical dinosaur, and he needs to become a bird.
Good arguments for the dinosaurs as IC being in Fixed Attitude or Manipulation/ Psychology probably both exist. For now, I'll focus on Fixed Attitude since it goes along with my last few posts. Specifically, Impulsive Responses.
I think it's fairly straight forward. As animals, the dinosaurs embody impulsive responses. When Alex calls them monsters Grant says, "They're not monsters; they're animals. They do what they do." And of course they inspire impulsive responses in Grant. It's not hard to imagine they're satisfying some innermost desire to see the real thing. Memory and Contemplation are more difficult to find, but they've certainly inspired contemplation in the lunch scene, and there's talk about how the raptor's "remember." And then you have a brief recollection from Grant about triceratops being his favorite as a kid.
I'm not entirely sure. I might be making more of an RS argument here. Sometimes I find it hard to see the difference between the relationship and the IC's influence on the main character.