Despite Stefan being positioned as being the "good" one, a scene in The Vampire Diaries season 5 proved that Damon was secretly always the better brother. The Salvatore brothers have a great relationship arc over the course of The Vampire Diaries' eight seasons. First starting out as bitter enemies, Damon (Ian Somerhalder) and Stefan (Paul Wesley) become reluctant rivals and occasional allies before finally forming a bond of genuine, unbreakable love for one another.
Damon often gets a bad rap from a number of other characters who trust Stefan implicitly while writing Damon off as self-centered and not worth saving. At first, it seems reasonable; when Damon is first introduced in The Vampire Diaries, he indiscriminately murders humans and generally is a jerk. Meanwhile, Stefan eschews feeding on humans and is compassionate. However, flashback scenes in The Vampire Diaries soon reveal that Damon had been the more innocent one in their past and that Stefan hadn't been the best brother to him. From that point on, audiences slowly start to see that it's actually Damon who is often the far more selfless brother, even if Stefan doesn't realize it.
A scene in The Vampire Diaries season 5, episode 9, "The Cell" revealed just how much Damon does to protect his brother from all forms of hurt, a thoughtfulness that Stefan rarely extends in return. Damon tells Elena (Nina Dobrev) about an incredibly dark time in his past in which he'd been kidnapped by the Augustine Society, kept in a cell, and experimented on and tortured for five years. It's horrific, the kind of thing that scars a person forever. At first, Damon had believed Stefan would find and save him. As the years passed, however, Damon realized his brother wasn't coming and he eventually escaped, though at a great physical and emotional cost. Surprisingly, though, Damon confesses to Elena that he's never told Stefan what had happened to him at the hands of Augustine. He's kept the horrible truth to himself, sacrificing his own well-being for his brother. The shocking revelation makes Stefan's treatment of Damon all the worse by comparison.
Earlier that same season of Vampire Diaries, Stefan is trapped in a vault and dropped into the quarry lake. For three months, he drowns over and over until he's saved by Qetsiyah (Janina Gavankar). No doubt, it's a hellish existence, but Damon's was worse and far longer. Yet, not only does Damon not hold a grudge against Stefan, his main concern is keeping it from his brother to spare him pain and guilt. Stefan, however, openly blames Damon for not rescuing him and wears his resentment on his sleeve. Even in the face of Stefan's unfair treatment, Damon keeps his time being tortured at the hands of Augustine to himself.
There are countless moments in The Vampire Diaries that reveal Damon is often a far better brother to Stefan than Stefan is to Damon. A similar instance is when they vow to enlist together to fight side-by-side during WWII. But Damon never shows after being convinced by Lexi (Arielle Kebbel) that he's a bad influence and it would be better for Stefan for him to stay away. As a result, Stefan thinks Damon abandoned him, estranging himself for years due to his bitterness. Still, Damon never tells him the real reason, not wanting Stefan to know it was his own best friend who had told Damon not to go.
Damon has always been willing to carry the burden of his brother's resentment in order to spare Stefan pain. Granted, Damon doesn't make it easy on himself. It's a Vampire Diaries tradition for Damon that he often shoulders the blame deserved by others rather than defending himself to a degree that's masochistic and driven by his self-loathing. But, as he's said in the past, he doesn't mind being the "bad guy" if it's for a purpose. Damon's purpose in The Vampire Diaries has always been to protect his brother, sacrificing his heart and reputation time and again to do it. That Stefan so rarely recognized it revealed exactly why Damon was the better brother.