I actually like that N gives his dragon away by the end of BW2,, I like to think that it symbolizes the end of N's whole character arc and him freeing himself from a destiny that had been forced on him,,, (big yap session under the cut)
In my opinion N only became a hero at the tail end of BW2. To me he doesn't become a hero the moment he awakens his dragon, and it's instead a years long journey. He always had the potential to be one, which is what triggered his dragon into awakening, but N needed help, time and healing to achieve it. I think that N is a hero by nature, for his heart is always in the right place, but it takes him two years to find himself after the damages done by Ghetsis.
N gets his legendary dragon following Ghetsis' lies, threatening the balance of the region. His resolve and his pride are so strong that he becomes willing to hurt the creatures he wants to protect in the first place ("I will prove the value of my beliefs even if it means my Pokémon friends get hurt!"). He is willing to use his friends as tools to prove himself right. I think it's the moment where we see that N isn't thinking for himself, but is entirely borrowing his values and morals from Ghetsis.
Once he and Ghetsis are defeated, instead of staying and taking the consequences on his actions, N ditches. He leaves his sisters, the grunts and Rood behind to pick up the pieces. When the people who trusted him needed him most, N fled. In a memory link event, after two grunts throw hands in the Safe House, N appears and notes that the grunts have been redeeming themselves while he fled and did nothing ("I've been worried about the people who believe in me... But it seems they know what they can do for Pokémon in their own ways. Compared to them.... What was I doing ? What I really should have done was tell people how Pokémon feel...!")
To me, the time N becomes the hero is when he stops Ghetsis from freezing a kid to death. I think that's the climax of his story, where he finally decides to face Ghetsis and work to redeem himself. I think that's when his ideal/truth actually shines the brightest. He fights for what he truly believes in after having found his own morals and values.
When Ghetsis is finally defeated and Unova is safe again, N gives away his dragon because he found himself and what he believes in !!! He served his purpose as the hero. He redeemed himself, and worked on himself to be the best version of himself. He can start being a person, free from the burdening destiny that Ghetsis forced on him since his childhood.
Idk I know that a lot of people think of this ending as bittersweet, or even tragic, but I tend to think that it's rather poetic and satisfactory ! N completed his self-discovery journey. He now fights for his own morals and convictions. He stopped running away from his problems. He faced and helped defeat the horrible man who made him. N was freed from Ghetsis' expectations to be the hero who shall serve his father's selfish goals. N can finally make decisions for himself and do what he thinks is right. He can choose his own path ! He dreams of a world were pokémon and humans live in harmony, and with Ghetsis defeated for good, he is a step closer to his ideal. He chooses to give his dragon to someone who might need help fulfilling their dream after he did so much progress on his own
In conclusion N is just a little guy but he works really hard to be a good little guy














