If you publish a story saying I fired that gun, my life will be ruined. I'll be banished from the Adventure Scouts, and charged with a misdemeanor. So, what if I have a better story? If I tell you what I know, promise me the gunshot stays between us.
Dilton presumably grew up in Riverdale. However, little is known about his home life, such as family, and he does not seem to have any friends. Dilton's biggest priority appears to be his devotion to boy scouts, although, recent events have shown that DJing at least seems to be a hobby of his.
A little more than 8 years before the events of the first season, eight-year old Dilton was revealed to have been going on an annual memorial weekend camping trip, a tradition begun by his father who had been an adventure scout. His father was unavailable due to a business trip, and had to ask his uncle Dan to take his place. On the second day of their trip, Dilton, his uncle Dan and a few of the other participants encountered an accident during the annual whitewater rafting excursion. His uncle's body was recovered later that day. As a consequence of those events, Dilton's father would become intent on his son being prepared for the worst case scenario to the point that he actually faked himself being tied down to an Improvised Explosive Device that he forced Dilton to disarm. In an even more severe case, he actually forced Dilton to blindfold himself before leaving him stranded in Fox Forest for at least nine days until Dilton worked up the courage to find his way home. 
Dilton was leading Riverdale's boy scout troop on a bird watching expedition throughout the woods located nearby Sweetwater River, when he came upon Cheryl Blossom on the river's edge, who muttered out "Jason" as the two of them make eye contact. He presumably contacted the local authorities immediately after. 
Dilton received an unexpected visit from Jughead Jones as he prepped the boy scouts for survival in the world. He was informed of the gunshot that both Cheryl Blossom and Archie Andrews claimed to have heard that morning at Sweetwater River. Dilton insisted that neither he nor his boy scouts heard anything unusual. He also denied seeing anything other than a couple species of bird, and Cheryl, sitting by the river's edge, soaking wet. He was later confronted by Jughead yet again, at the Taste of Riverdale. He fired the gun in the woods that morning, but lied about doing so, in order to protect himself. Jughead gave him two options, confess to Sheriff Keller or confess to him and Betty. Wisely, Dilton chose the latter. Hoping to salvage his reputation, Dilton offered Jughead and Betty Cooper another story, one he claimed to be better than his own. They agreed and he wasted little time revealing that he saw something up on the river that no one else did on July 4th: Ms. Grundy's car. 
Presumably at Chuck and Cheryl's request, Dilton DJ'd the party being held at Archie's house, which was initially suppose to be a small surprise party for Jughead. As the dancing came to an end, so did his DJing, once the party shifted its directions towards something a little more devious, a game called "Secrets & Sins", and each of them would reveal their secrets. Dilton was one of the first to volunteer, in which he revealed to the entire party that he saw Ms. Grundy's car at Sweetwater River on the day that Jason disappeared, and that just two days after informing Jughead and Betty of this, Ms. Grundy quit her job and left town. He went on to remind everyone that Archie was also at the river that fateful day. 
With the shooter, now known as the Black Hood, striking yet again by shooting Moose and Midge at Lovers Lane, Dilton met up with Archie, Reggie and several more of their classmates in an empty classroom to collectively discuss their next course of action. They were under attack, and needed a plan best suited to stopping Black Hood. This time it was Moose or Midge, but next time, it could just as easily be one of them or someone close to them. Archie suggested that they start a watch group to focus on Riverdale High School, which would act as an extra circle of protection for students, staff, and their parents. No weapons. No violence. They would merely be an extra set of eyes and ears for the police. What if we run into the killer, Dilton asked, as he whittled away at a wooden object. Archie told them to call Sheriff Keller should they come face to face with the shooter. They're not vigilantes. They're watch dogs, and officially, they're called The Red Circle.
Later that day, Dilton and his fellow Circle members began passing out and hanging up flyers, instructing residents to call them should they need protection or just felt afraid.
A couple days after forging the Red Circle and putting forth their best effort in keeping the town safe, Archie decided it was time to go on the offensive. Dilton recorded while Archie and the rest of the Red Circle members, all of whom were wearing red masks, sent the Black Hood a message, telling him that Riverdale was a lot stronger than he was and attack from the shadows would only work for so long. They weren't afraid of him. There was only one of him, but they are legion, and they are coming for him.
The Red Circle gathered in the boys locker room after learning that Mr. Weatherbee was threatening to permanently suspend the entire football team should Archie continue with his refusal to disband the Circle. Unfortunately, Archie refused to submit as that would make them appear weak and helpless in the eyes of the Black Hood. Archie wanted to force the killer's hand by going to his home turf, the south side. Archie came to this conclusions after realizing that the Black Hood's victims were all Northsiders. He believed that going to the south side was their best chance. The hunter becomes the hunted, Dilton remarked. Unfortunately for Archie, the rest of the Circle didn't share his sentiment, though Dilton did offer slight assistance. He was aware of Archie's plan to take on the Black Hood himself, a fight to the death. The Red Circle was just Archie's way to draw the Black Hood out, and now he wants to make his presence known in the killer's territory. Should Archie go down this route, Dilton directed him to the U.S. Army & Navy gun shop on the edge of town.
Dilton sat in class, as Archie was pulled into the hallway by Mr. Weatherbee and Sheriff Keller for questioning. Later that night, after learning that Archie covered for Reggie, the Circle paid him a surprise visit at his house to tell him that after some deliberating, they've decided to stand by Archie in his quest to keep the group together. It was then that several members of the Southside Serpents, led by Sweet Pea, arrived outside of Archie's house, looking for a fight, which Archie was more than happy to oblige.
The Red Circle and the Southside Serpents took the fight to a vacant lot, where a brief stand off took place before chaos ensued, starting with Archie landing the first punch on Sweet Pea. From there, all hell broke loose as the massive Rumble got a bit out of hand, especially on Dilton's end, as he was taking a beaten from the Serpents, forcing him to pull out a knife to defend himself. The fight went on until Veronica fired off a single shot from Archie's gun into the air. Unfortunately, everyone wasn't lucky enough to make it out of the rumble with nothing more than a few scratches and bruises. Dilton had been stabbed in the leg and was rushed to the hospital by Reggie, who told Dilton to tell the doctors that he was randomly attacked by Southside Serpents.
Dilton is a lean young man of medium stature, who has pale skin, black hair and brown eyes. He's very skinny, but a hardcore survivalist at heart. Dilton is often seen wearing glasses, and his Riverdale boy scout troop uniform.
Being a hardcore survivalist, Dilton believes in doing whatever necessary in the course of standing his ground. With the direction Riverdale was headed in, he thought it best to teach young children how to fire a gun, which he later lied about to both Sheriff Keller and Jughead Jones, making him both a liar and public menace. Dilton is also quite the opportunist, he held on to the information that he had of Geraldine Grundy being at Sweetwater River on July 4th, until revealing this served him best.
Dilton Doiley and Reggie Mantle are currently the only two characters to be portrayed by two actors.
In the comics Dilton Doiley, is a geek who is frequently harassed by Reggie Mantle and shares a close friendship with Moose Mason; he is also not much into girls, though he dated Cheryl Blossom in the 90's comics after they were paired online due to sharing similar interests.