Neville is an amazing friend to Harry, from the very start of the story. In Second Year, when Harry is completely isolated within Slytherin and Neville awkwardly reassures Harry that he doesn’t believe he’s the heir.
The way Neville casually forgets Harry is the Boy-Who-Lived, and all the ramifications of that title. Even after the reveal of the prophecy, to Neville, and to Harry’s other friends, it simply does not matter.
Neville’s complete bewilderment at being accepted in the Slug Club, and Harry’s subsequent, and entirely genuine reaction:
Neville: Did you hear that? He said he was sure I’d go far! Why would he say a thing like that?
Harry: Because you will.
Fred and George teaching Harry the true meaning of friendship:
Maybe that’s what friends were for: despite not having solved any of his problems, Harry felt better for having talked to the crazy duo anyway.
Harry’s fierce defense of Luna is heartwarming in itself, he always makes sure that no Ravenclaws think it's okay to pick on her for being different (while also admitting she’s completely bonkers).
Blaise and Millie officially forming the Power Trio in Slytherin with Harry. It’s in Slytherin, so really that meant crossing the common room to sit with him, but subtlety is key to that kind of politics. Considering the number of future Death Eaters in the room, it was a rather big message to send.
Snape, who as his Head of House genuinely does try to look out for him, and understands him much better than the Canon Harry. A lot about what it means to be a Slytherin amongst the ‘good guys’ and particularly Harry’s fascination with Dark Magic. He’s Snape, and predictably sour about it, but when Harry is struggling, he helps him, not just as the Boy-Who-Lived who he’s sworn to protect, but as just another Slytherin who might be lured to the dark by Voldemort. Slytherins stick together.
Such as careers advice, in which Snape completely snaps when hearing Harry’s lack of plans for the future. (Due to Voldemort and everything, career prospects weren’t at the forefront of Harry’s mind.) Snape quickly points out that making plans for his future will significantly increase his chances of having one. It’s very clear at this point that Snape is very invested in making this happen.
Snape: Have you actually entertained a ‘’thought’’ for your future, Potter?
His one and only acknowledgement of Harry’s exceptional Potions skills – not checking to see if Harry is brewing the correct potion while he rattled off instructions to save Dumbledore’s life.
Snape teaches Harry total control of both his magic, and other unpleasant impulses that come with Dark Magic addiction.
Harry left the classroom uncertain whether he’d just received a schooling or the best offer of help that had come his way in recent times.
Harry’s happiness at beating Gryffindor in Quidditch, he even plays nice with Malfoy for God’s sake. It’s at the peak of a very stressful time for Harry, and he deserves a bit of deserved happiness:
For the first time in a long time, he felt like they were all just kids celebrating a sports victory and not giving a damn about anything that went on behind the school walls. Not a bad feeling at all, as it happened.
Ron of all people comes to Harry’s defense after Skeeter’s article breaks. This conversation, especially in the context of the original series and the development of their relationship here, is more than a little heartwarming. After years of coldness, they finally get a bit of banter:
Ron: You’re alright, Potter. For a Slytherin wanker and all.
Harry: Thanks, Weasley. That’s what I call a real compliment.
And again defending Harry against Bill and Charlie’s criticisms:
Ron: You’re not at school, you don’t see what it’s like. Potter is doing a really good thing there…
Cedric doesn’t ask questions or hesitate to help when Harry knocks in the middle of the night. His advice is sincere and unbiased and exactly what Harry needs to hear.