Like that's such a loaded thing to think about. He's got so much resentment built up. Obviously, there's no direct connection to any of Tsuna's issues made but I think a few fun things can be said from this. In general, Tsuna clearly didn't have a father figure in his life which sorta results in him leaning on Reborn pretty often. Tsuna doesn't have a very stable self-esteem with him going from confident to "Aah, Gokuderas going to become disillusioned with me now that all my flaws have been pointed out." GOKUDERA. His FIRST SUBORDINATE. The guy who literally has been LOYAL FROM DAY ONE. Not that we consider them canon, but this happens also during the filler arcs where Daemon points out that Tsuna's not worth following to Gokudera and it seems to make Tsuna a little antsy. He DOES NOT THINK THE PEOPLE HE LOVES ARE GOING TO STAY WITH HIM, THIS IS LITERALLY RUINING MY LIFE. What Daddy Issues DO TO A MF. But that's a post for another day. But okay, back to Reborn, Reborn proves himself to be immovable from Tsuna's life. The story points out that Tsuna very much has two fathers. The one who won't leave and the one who is always gone. Tsuna really leans on Reborn throughout the series. "Reborn, what do I do?" Is a common thing he says, until Reborn is literally swept away from him against his will in Future arc where he's forced to think that he's half a person in Reborns absence. Meanwhile, we have Iemitsu who Tsuna has resentment built up towards, does not respect, and is forced to acknowledge in order to win his fight. Throughout the rainbow arc battle, they try to point out that Iemitsu is trying to teach Tsuna something here and unless I'm confused (someone feel free to tell me?) it's not really clear WHAT that is. And I've always thought that was neat, because it's obviously coming from Tsuna's inability to respect Iemitsu enough to want to learn anything from him. Yet when Reborn comes in, hell he doesn't even recognize him in his Adult form, but he politely listens and takes his advice seriously. In the grand scheme of the series, Reborn is a good teacher and father figure in his life. When Tsuna is made to feel like that he can't do anything in Reborn's absence during Future, Reborn takes a step back in that arc and lets him learn to survive without his guidance. (Notice how the training almost entirely disappears after Future.) He lets him learn how to be a person without him, only stepping in to help when Tsuna really needs it. When he's unable to light his flame, with Spanner, or when he's freaking out about the Irie reveal, the list really goes on. There's a scene I recall I believe when Yuni asks to join their group, Tsuna still turns to ask Reborn what to do, and Reborn redirects him by asking him what he wants to do. That it was his call as a boss. And Tsuna ends up making the decision to help her off his own accord.
It's with Reborn's guidance that Tsuna ends up learning to be his own person, it's this guidance that allows him to make the decision and gather everyone on his own accord when it was Reborn's turn to be shaky and give up. Where Tsuna tells him that he's got this under control, without his guidance. To just watch him. "you've always knew I could win before." It's this arc where Reborn's pride in Tsuna shines. Multiple times. "Surprise me again, Tsuna." And he does. It's in Reborn's second absence where Tsuna feels himself get shaky again, feels the old feelings of poor self image crop up, that Reborn comes back. Because Reborn is not Iemitsu, and he wasn't someone who left him in that house alone forever. Because he's still young and has much to learn before he's ready to do this on his own. It's at this he feels a little embarrassed about how glad he is that Reborn came back, but then recalls the "mean words" that Reborn said before leaving. It's here that Reborn tells him it's a good thing he hasn't changed much. Another sliver of guidance that Tsuna takes in from the figure in his life that won't leave him alone in that house.
