Introverted Feeling (Fi): Matt is constantly ruminating on his feelings, whether it’s his infatuation with Allison or his feeling hurt and traumatized over having almost drowned to death as a child, and his internalization of these strong, negative emotions is what drives him to become a villain. He fixates on his feelings, to the point of growing obsessed with Allison, and it is hinted by Stiles that Matt explores his feelings through creating fantasy worlds by photoshopping himself into photographs with Allison. Matt admits that, following having almost drowned at a party when he was just a child, he had kept his fears and despair to himself for years, and had never even told his parents about his traumatic experience, but eventually his feelings overwhelm him and he can’t help but act on them. Matt is firm in his feelings for people - even though he’d been hurt by the Beacon Hills High School swimming team many years ago, he stills believes the alumni of the team to be bad people. He doesn’t, however, hold grudges against the people connected to them, for example, he doesn’t hurt Isaac, despite the fact that it was Isaac’s father and brother who had hurt him, because Isaac didn’t hurt him. Matt isn’t good at reading other people’s emotions, despite how sensitive he is to his own feelings - he can’t tell that Danny has a crush on him even though it’s obvious to Jackson (who uses Fe).
Extroverted Intuition (Ne): Matt embraces the ideas of kanimas, werewolves and hunters as he learns more about what is really going on around him. He is eager to take in new information and explore these new worlds, being curious about the world around him and running with new information and ideas as he’s presented by them. He discerns a pattern in the way certain events had unfolded which leads him to discover the connection between the kanima and himself, and eventually that Scott is a werewolf and that Allison comes from a family of hunters. He’s got a big, although twisted, imagination and spends time photoshopping himself into pictures of Allison, which indicates that his imagination is excited by external stimulation. Matt is curious about the world around him, so much that he was even willing to spy on Jackson through the of the camera he had loan him, and he pays attention to new possibilities as they arise.
Introverted Sensing (Si): Seeing somebody who’d hurt him in the past brings back his deep-seeded anger and throws him into the past. Matt is so haunted by his experience of almost having drowned as a child that the mere sight of somebody who he felt was responsible for his drowning, Isaac’s father, leads him to revisit old feelings. Matt can recall specific things that were said to him and the exactly way certain people (the 2004 Beacon Hills swimming team) had treated him, using his experiences with people as a frame of reference. Matt is very invested in his hobby of photography, which he states comes from him wanting to make a memory imprint of anything that “catches [his] eye,” rather than in the more artistic Se sense of capturing the aesthetics of what’s right in front of him.
Extroverted Thinking (Te): When his actions cause things to go awry, Matt attempts to take control of everything around him, using force and intimidation to reach his goals. He springs into action, digs in his heels and takes charge of the situation, threatening Scott, Stiles and the sheriff to destroy all of the evidence that he is a killer, and demands answers when he can’t figure out what’s going on with him (when he begins turning into a kanima). As Matt learns more and more about the world around him, specifically that he is the one who controls the kanima, he finds ways to selfishly put his power to use when his extreme negative emotions are triggered.
You pressed your back against the wall, your eyes wide open and your heart racing in your chest. “What is that?” You stuttered because of the fear, feeling how you knees were trembling, how your entire body was shaking, how you were more afraid that you had ever been before. “Easy, girl, easy, he’s not gonna hurt you.” Matt placed a hand on your shoulder, but you didn’t feel too comfortable, still staring at that thing with sharp teeth and strange eyes staring at you. “He doesn’t look like he’s not gonna hurt anyone.” You whispered and heard how Matt started to laugh, caressing your shoulder, shaking his head. “I never said he’s not gonna hurt anyone.” Matt whispered in your ear and you turned your head, frowning your eyebrows, not knowing what he was talking about. “How can you be sure he’s not gonna hurt me if you’re not sure he’s not gonna hurt anyone?” You turned your head back to the monster, waiting, as if he was waiting for a command, waiting for someone to tell him what to do. “Because he only hurts who I want to get hurt.” Matt smiled and you raised your eyebrows, not believing what you were hearing. “You’re telling that who to hurt?” Your muscles strengthen and all of a sudden the nice Matt you fell in love with was seen through different eyes. “I don’t have to tell him, I can just think about it.” His voice sounded calm, calm and happy, as if he had been waiting for something like this for months, for years, for maybe even longer. “I think of the people I want dead and he does it.” The coldness in his voice made you shiver, made you realise that this was a side of Matt you had never wanted to see, had never wanted to get to know. “Are you out of your freaking mind?” You yelled out loud, for a moment forgetting that if Matt would think about killing you, the monster was only inches away to do it for him. “You don’t know what they did to me!” Matt turned towards you and you saw the panic in his eyes, the panic caused by memories, memories that were clearly still hurting him. “You’re not a killer, Matt.” You whispered softly, placing a hand on his chest, your other hand against his cheek. “Sometimes it can be tempting to solve your problems like this, but you’re better than that. You’re better than using a monster to do your dirty work.” You saw his eyes softening a bit and his hands pressed against your shoulders. “I can’t help it.” He spoke softly and you shook your head. “I just have to think about it and he does it.” He pointed towards the monster and you sighed, knowing that it was easier said than done to change your mind. “Change it, Matt, I know you can change your mind.” You cocked your head and saw a sigh escaping his lips. “I’ll try.”