How we cite our quotes: (Part.Paragraph)
Quote #1
I return to the cafeteria and sit down at the Abnegation table, among the people who barely know me. (1.17)
Here we see early on that Tobias/Four doesn't have any friends. He makes no conversation with the people at his lunch table.
Quote #2
[The Dauntless] are so loud and wild. Can I possibly make a place for myself among them? I don't know. (1.192)
The prospect of having to socialize is scarier to Tobias/Four than jumping down a pit or going into a fear simulation.
Quote #3
"Joining a faction is about more than getting through initiation, you know," Amar says. […] "For most of the Dauntless, they meet their best friends during initiation, their girlfriends, boyfriends, whatever." (2.9)
Joining a faction feels like a fraternity hazing, people going through a series of rituals in an attempt to make friends. Except in this world, it's mandatory.
Quote #4
It's camaraderie and friendship and flirtation, and none of it is familiar to me. (2.22)
Friendship is puzzling enough to Four. No wonder he's so bad at romancing Tris later on. He doesn't get social cues at all.
Quote #5
I should feel satisfied, not afraid. Maybe even happy, to finally belong somewhere, to be among people whose eyes don't skirt mine at the lunch table. […] What is the cost of being Dauntless? (2.155)
Friendship is a double-edged sword. Without friends, Four only had to look after himself. Now he's responsible for helping and taking care of others too, people he cares about.
Quote #6
"Lesson one: It's okay to hug your friends here."
"We're friends?" I say, only halfway joking. (2.199-2.200)
This is the first time someone refers to Four as a friend. He tries to play it off as a joke, but he's genuinely surprised.
Quote #7
"I'm surprised you didn't choose to room with your fellow former initiates. You did make some friends, didn't you?" (3.7)
Even though Four has made friends by this point, he'd still rather keep them at a safe distance. Living with someone is a step he's not yet willing to take.
Quote #8
If the factions are deteriorating, as my mother would have me believe, this is not a bad place to watch them fall apart. At least here I have friends to keep me company while it happens. (3.355)
Four's friends are like the net at the bottom of the Pit—even when something scary is about to happen, like a difficult choice Four has to make about his future—his friends will be there to catch him.
Quote #9
Then [Tris] turns and runs to catch up with her friends. (4.294)
This is a nice contrast between Tris and Four. She makes friends fairly quickly into her initiation, unlike Four. For him, friendship was one of the hardest parts of the whole ordeal.
Quote #10
"It must be because you're so approachable. You know. Like a bed of nails." (6.57)
Tris's sarcasm is pretty spot-on. She zeroes in on Four's prickliness, which initially made it very difficult to make friends. But Tris can spot this because she is the same way. The difference is that she doesn't use this attitude against people she actually wants to be friends with, a social skill Tobias/Four lacks.