No one knew exactly how hard Garth worked to be like Bobby, he busted his ass every day and still found happiness. He found it in the open roads he traveled. The hunters he fought with. He had no beef with anyone, not even the monsters he genked. He killed them because he believed that was what needed to be done. No vampire killed his girlfriend, he didn't swear revenge on every monster.
He did it mostly because he yearned to help, he had no underlying motives. He did it not to take Bobby's place but to be an extension, a helping hand wherever he was needed, giving information to every hunter he knew. Playing the FBI director and all the other aliases that Bobby left behind.
Nobody questioned Garth's work until the Winchester's, specifically Dean, showed up on the case he happened to be working. Constantly judging Garth and everything he did, trying to destroy his name, everything he had been working towards since Bobby had died. What Dean didn't seem to understand is Bobby was involved with more people than just him and his brother. His death affected more people than just them. Hell, there were hunters that still didn't know.
It took Garth three days to finally convince Dean that he was worth it, that he related to Bobby in any way. It took a particularly vengeful spirit and a realization on Dean's part. Garth was always happy because he held no grudges with anyone, during his time as a hunter he learned to forgive and forget.
People may think he acts a little ridiculous but it's because he found true peace in his life. He is almost certainly the most remarkable hunter in the game, he doesn't let his past haunt him, he moves on. That is what makes him different from Bobby, Garth may have picked up his dialect but his peace will always make him different from the others that live the life he does.
A/N:
I watched the newest episode of supernatural and it inspired me. It made me realize what Garth does, that on the outside he's a goofy comic release, but on the inside he has found true peace.