Otis prefers animals to people. He's unusually quiet, and he only agrees to go to Opal's party because she promises him he won't have to talk. Stevie Dewberry claims he's "retarded," but that's not true (13.8). It's probably just some extreme social anxiety
Plus, Otis has a dark past. He spent time in the slammer. What for? Well, just for playing the guitar—or, actually, punching a cop. Not a good move, but not exactly moral depravity. Still, the label "ex-con" haunts him and makes others avoid him and talk about him behind his back. Even Opal wonders if she "should be afraid of him [...] For being in jail" (14.9,11). Hmmm… judgment, rumors, fear… sound familiar? If you're not sure what we mean, check out Boo's and Zero's character analyses.
People are scared of Otis because of what they don't know about him. Same for Zero. Same for Boo.
In Otis's own words, "I ain't a dangerous man…. I'm lonely. But I ain't dangerous" (19.16). The truth is, like a wild animal, Otis is more scared of other people than they are of him. He used to conquer that fear by playing guitar for people in the street. That made him happy.
It also landed him in jail. Talk about shattering the Trust-o-Meter.
So now he only plays for the animals. He misses other people, but he can't bring himself to face them. What if they betray him again? Better to be safe inside the pet store. Alone.
In the end, Opal and Otis save each other. Let's look first at how Opal saves Otis.
Instead of avoiding him, she listens to Gloria's advice about the alleged criminal: "you can't always judge people by the things they done. You got to judge them by what they are doing now" (14.40). And what he's doing is charming the animals with his guitar and taking really good care of them. Even Sweetie Pie thinks he is "magic" when he plucks those strings (12.21).
When Otis tells Opal the truth about his (not so) dark past, she finally "gets" him. She sees his lonely heart. That's why she plans the party—to give him a chance to play for people again. She sees how scared he is, and she treats him gently.
"I brought pickles," he said.
"I saw them," I said. "It's just exactly what we needed. They will go perfect with the egg-salad sandwiches." I talked to him real soft and gently and low, like he was a wild animal that I was trying to get to take food out of my hand.
He took one tiny step forward. (21.23-25)
By the end of the party, Otis smiles, plays guitar, and "looked all lit up from the inside" (25.22). Looks like Opal saved another loner. And it's not a one-sided relationship, either. He saves Opal by finding Winn-Dixie, because:
• His music coaxes a grin out of Winn-Dixie, even in the thunderstorm.
• And a grin sparks a sneeze.
• A sneeze prompts a search party.
• And voila! Lost dog found again.
In other words, by helping Otis find himself, he helps Opal find her most precious possession. And there's nothin' criminal about that.
Here's the nutshell version. Because of Otis, Opal:
• finds Winn-Dixie
• learns songs
• enjoys beautiful music every morning
• makes a friend
• learns to look beyond rumors
In short, thanks to Opal, Otis:
• starts trusting people again
• escapes his loneliness
• escapes his shyness
• feels love and acceptance
• finally belongs