Although he only appeared in two episodes, Otis was shown to be a kind, generous, capable, brave, and unselfish person. He was clearly loved very much by his wife Patricia and was a cherished friend to Hershel, Maggie, Jimmy and Beth who were all devastated by his death. Otis was extremely remorseful for his accidental shooting of Carl Grimes and made it a personal mission to help Shane retrieve much needed medical supplies to save the boy's life, although it tragically resulted in his violent death as a result of Shane.
Before the outbreak Otis was employed by Hershel years back as a ranch foreman. At some point, he also became an occasional volunteer Emergency Medical Technician who worked with the local fire department. Otis had a wife named Patricia and presumably the two of them lived in the same house as the Greene family. He also knew how to play the guitar and was interested in the sport of hunting.
Otis was in the woods hunting for a deer to feed his fellow survivors. He tracked a buck and shot it, but the bullet passed through and hit Carl as well. Otis took Rick Grimes, Carl, and Shane Walsh to Hershel's farm where they discovered that Carl was critically injured by the bullet, suffering internal bleeding. Feeling immense guilt for shooting Carl, he took Shane to a nearby former high school, now a FEMA command post, to scavenge for the needed medical supplies. Upon reaching the school, they discovered that the school had been overrun with walkers. Using road flares from a nearby police interceptor, they created a diversion to lure the walkers away from a medical supply trailer. Inside the trailer they were able to find all of the supplies needed, but upon leaving it, they discovered that the walkers had lost interest in the flares and were once again swarming around the trailer. Otis and Shane made a run for safety, hoping to make it back to Otis's truck. They were cut off and forced to break in to the school, shutting themselves inside with the security gate.
The walkers broke through the flimsy security gate and pursued Otis and Shane through the hallways of the abandoned school. Otis and Shane ended up in the gymnasium and were able to take refuge on top of the bleachers and formulate a plan. Otis thinned out the group of walkers, while Shane busted through and jumped out of a nearby window. Otis, who was too overweight to fit through the window, took advantage of the diversion that Shane made, and jumped down and made for the locker room where he was able to find a larger window to break out of. Otis and Shane eventually met up outside of the school, but continued to be pursued by a group of walkers.
The two grew fatigued and Shane faltered, pleading for Otis to take the medical supplies and go on without him. Otis refused, helped Shane to his feet, and pressed on. The pair quickly ran out of ammo and were forced to resort to their pistols. However, they were moving too slowly to effectively outrun the horde pursuing them. Shane, knowing that Otis would likely doom them both and Carl, decided to shoot Otis. Shane and Otis scuffled over the supplies, with Otis ripping out a chunk of Shane's hair. Shane prevailed and limps away, while Otis was eaten by the walkers.
"You were the last one with him. You shared his final moments. Please, I need to hear, I need to know his death had meaning"
—Patricia begging Shane to describe her husband's final moments.[src]
Otis and Patricia were married and loved each other deeply. Otis told Patricia he had to go and help get the medicine with Shane for Carl since it was his fault he got shot. While Otis was gone, Patricia worried about him. When Shane came back and told Hershel Otis was dead, Hershel told Shane that he would tell Patricia after she helps Carl because he needed her help. After Carl was patched up Rick and Hershel told Patricia the news, she bursts into tears. The next day at Otis' funeral. Patricia asked Shane to say some words since he was the last person with Otis and appeared to be pleased to hear Shane's concocted story of Otis' apparent sacrifice for Carl. Patricia never learned of the true nature of her beloved husband's death.
"Blessed be God, Father of our lord, Jesus Christ. Praise be to Him, for the gift of our brother Otis, for his span of years, for his abundance of character; Otis, who gave his life to save a child's, now more than ever, our most precious asset. We thank You, God, for the peace he enjoys in Your embrace. He died as he lived: in grace."
Otis was Hershel's close friend and they got along with each other well. Hershel is grateful towards Otis for helping him at the farm on numerous occasions, and doesn't mind him staying. Hershel was saddened of Otis' death, and held a funeral for him in appreciation for what he had done for his entire life and what he did right before his death. It is unknown if Hershel was ever told by Rick or Lori of the true circumstances of Otis' death.
Maggie knew Otis very well since she was little, implying they were close and very good friends. When Maggie learned that Otis had died while trying to get medical supplies to save Carl, she broke down into tears, showing just how much she cared for him. It is unknown if Maggie was ever told by Rick or Lori of the true nature of Otis' death.
Otis and Shane only knew each other for a very short time, though it is clear that Shane despised Otis for accidentally shooting Carl. Soon after they met they were forced to work together in order to retrieve medical supplies to save Carl's life and Shane appeared to show respect and gratitude for Otis' willingness to help. However, with a herd pursuing them and unwilling to let Carl die, Shane chose to sacrifice Otis to the Walkers as bait to secure his own escape, causing Otis to die a horrible and painful death. However Shane apologized to Otis before doing this, indicating he somewhat appreciated Otis' efforts to save Carl and the fact that Otis was a good man. Shane even showed signs of disdain for Otis' death while out searching for Sophia with Rick, claiming that Otis paid the bill for Carl getting shot while out looking for Sophia.
Shane also showed signs of suffering from denial of guilt following Otis' death, and partly because of this developed a much darker personality over time. Overall however, Shane showed little remorse for what he did to Otis, and lied to the group about Otis' death and later told Rick that one of them was going to die that night at the high school and it was going to be Otis and that he had no business being there with him and Shane overall believed Otis' death was necessary to save Carl's life.
—Rick offering gratitude to Otis for volunteering to save Carl[src]
Rick and Otis only knew each other for a short time, but it is clear that Rick initially hated Otis for accidentally shooting Carl. Otis was clearly remorseful about accidentally shooting Carl, however, Rick seemed completely indifferent towards him out of concern for his son. Rick eventually learned to forgive Otis when he offered to go on the supply run to save Carl's life and tried to offer gratitude which Otis refused until Carl was up and about again. Rick gave Otis his Colt Python before he left, and Otis promised to give it back to him in good shape. Rick was clearly remorseful when he learned of Otis' death and apparent sacrifice for his son, and consoled Shane by claiming Otis died while trying to make his actions right. Rick also assisted Hershel in telling Patricia of his death.
Rick did not learn the full nature of Otis' death until "Triggerfinger," making him realize that Shane was dangerous. It is unknown if Rick was angered of Shane's decision to sacrifice Otis to save Carl, though he most likely wasn't as he claimed he too would have done anything to save Carl's life.
Otis and Lori were never shown together, but it was clear that she was mad at him for shooting Carl, and called him "The idiot that shot my son". After Otis' death, Lori seemed to show some remorse and was clearly shocked to learn that it was in fact Shane who sacrificed Otis to the Walkers not just to save Carl's life, but because Shane loves her as well.
"Wait 'till that boy of yours is up and around, then we'll talk."
—Otis refusing Rick's gratitude of volunteering to save Carl[src]
Carl never had a chance to meet Otis, as he was already unconscious after being shot by him. Otis felt remorseful for shooting Carl, and offered to look for medical supplies that could save Carl's life. Shane states that if it wasn't for Otis, Carl wouldn't have survived, although Shane truly did not mean this as he sacrificed Otis to the walkers in order to secure his own escape and told a false story that Otis willingly sacrificed himself to save Carl.
"What, are you gonna shoot me like you did Otis? Tell another story?"
—Dale mentioning Otis while confronting Shane[src]
Otis and Dale never met each other, but Dale was clearly very upset by the death of Otis in order to save Carl. Dale was the only member of the group who did not fall for Shane's lie about Otis' death (aside from Daryl) and seemed very angry about the atrocity committed by Shane.
He is also the first member of the Greene farm group to die.
Prior to his death, Otis discovered the zombified Sophia and placed her into the barn at the Greene family farm. On Talking Dead, Robert Kirkman stated that the scene in which Otis located the zombified Sophia and placed her into the barn on Hershel's farm was actually filmed as a flashback.
The timing of Otis putting Sophia in the barn means that she was already dead before the end of "What Lies Ahead", presumably during the day or night following her disappearance.
Although, Otis was killed by walkers, it was caused by Shane shooting him and leaving him as bait. This makes Otis technically the first murdered victim of the series as Shane purposely had him killed.