Accident was one of the three starting Pokémon that was offered to Radic. Because Radic was in such a hurry to continue on his way, he put the ball back without watching what he was doing, and his finger slipped and touched the button on the front. Once the ball was open, the choice was made, whether or not he wanted it or not, and so Radic "chose" a Squirtle. Frustrated and angry that he had been given a Pokémon, much more one as important as his starter, that he had not consciously chosen, Radic decided to call his Squirtle Accident.

Despite this awkward and unhappy initial meeting, Accident soon proved his worth and Radic soon realized that he had indeed made the right decision. The two of them became close, and Radic, having had such a change of heart, asked Accident if he wanted to change his name. Accident refused, explaining his reasoning in metaphors that only Squirtles truly understood. Radic would never get a chance to ask him to explain.

While in a cave, Radic and his Pokémon were weak and lost when Radic tripped over a Geodude. Panicked, his three Pokémon at that time, Accident, Nova, and Callima, struggled to defeat the rock Pokémon, but had little success. Finally, with no other option, Accident launched himself forward and headbutted the Geodude into unconsciousness. The battle won, Accident then evolved, but seemed somewhat confused...

When taken back to the Pokécenter, it was discovered that striking the Geodude so hard with his head at such a young stage had given Accident permanent brain damage, erasing almost all his previous memories except that of Radic, his master, and his loyalty to him.

Radic felt intensely guilty and held himself responsible for what happened to Accident, but Accident does not blame him in the least. He does not really remember what happened, and those who were there at the time do their best not to remind him of it. Accident continued to fight and travel with Radic, forever trapped in a childlike mindset. He greeted all his new teammates with enthusiasim and kindness, and was always nothing but friendly to everyone he met.

Some time later, Radic and his Pokémon went on a cruise on the St. Anne where Accident met Aktarax, another trainer's Blastoise. He quickly developed a crush on her, the first he'd ever had, and she just as quickly exploited it and his good nature. Plying him with Rare Candies, kind words, and a weak sedative, she was able to get Accident to do whatever she wanted, including breeding with her and evolving. Accident's evolution was painful and confusing as most evolutions are, but this in particular wounded him deeply when he went to find Aktarax later, expecting some kind of comfort or relationship, only to find that she now pretended not to know him. She just wanted to use him for eggs. Not that Accident understood things that deeply, or what he'd done with her exactly, but it hurt him very badly. It's a dark and unhappy period in Accident's life, so he doesn't think about it. He has almost all but forgotten it, with only a lingering fear and dread about boats that he can't shake being the final remnants of it.

Through it all, Accident survives. He's a great fighter, surprisingly strong and resilient, and he's willingly followed Radic everywhere. He trusts Radic to take care of him, no matter what happens, and is intensely, fiercely loyal. It's because of this that he began to dislike Red and his Pokémon...because Radic constantly talked about how much HE hated Red and his Pokémon. When Radic and Red challenged each other to a battle, Accident was eager to make Radic proud. This was the first time that he faced Ratty in combat, and while Accident tried as hard as he could, succumbing to a blind rage when badly wounded and in pain, he still lost.

Accident felt bad about this, but Radic reassured him that they would beat Red someday. Accident still believes in this promise, and he still tries his hardest because he knows someday, he will beat Ratty and make Radic proud. The fact that Radic and Red's relationship has changed is something that's mostly lost on him...the frustration and anger he feels towards Ratty are easier to understand and follow.

Accident is cheery and upbeat almost all the time, completely oblivious to most of what goes around him. He's positive and optimistic in almost every situation, sure that they'll get out of it somehow, or Radic will know what to do. On occasion Accident can be stubborn about certain things or decisions, and in these cases it's impossible to change his mind.

Accident doesn't understand true evil or hatred, although because the two of them fought so fiercely and so strongly, Accident does feel something close to hate and fear of Ratty, who gave him a permanent scar on his neck. Deep down though, Accident believes that everyone is essentially good, and he doesn't believe in evil Pokémon. He trusts almost everyone he meets immediately and finds the world a wonderful place to be, filled with wonderful people. This can easily get him hurt, but thankfully Accident has his teammates and Radic to watch out for him. Hurting or insulting Accident is a sure way to get any member of Radic's team angry, no matter how aloof or cruel they can be otherwise. Everyone feels protective of him, although Accident doesn't understand why.

Accident is one of Radic's strongest Pokémon and Radic places much confidence in him. While generally happy and outgoing, he's still shy around new people and new Pokémon, due to his name. The idea of changing it hasn't occurred to him and probably never will. It's simply his name, that's how it works.

Accident doesn't hate any of his team-members and doesn't understand why they don't get along.

Accident has been in Together Forever, An Epic Battle, Aftermath, and basically almost every fic where Radic was with his Pokémon.

He has been mentioned in Howl of a Growlithe and other fics.