Some TMNT stuff really isn't for little kids.
In the TMNT series released by IDW Publishing, Casey Arnold Jones is a young college student on a hockey scholarship. He had more love for his sports activities than his studies, as well as a keen love of vigilante street fighting.
Upon his mother's death by cancer, his father became an alcoholic thug who would vent his daily frustration by beating his son. Casey did not fight back, due to a promise he had made his mother. On one such occasion, Casey was saved by Raphael, who at the time was a street vagrant with no memory of his past or his family. The two quickly became fast friends and fellow vigilantes.
When Raphael was reunited with his brothers and their father Splinter, Casey gained them as friends as well. He and Raphael would regularly patrol the streets of Brooklyn in search of crime to punish, which is where they first stumbled across the Foot Clan mutant Alopex.
Around this time, Casey met April O'Neil, who wanted to take self-defense classes from him after her traumatic experiences at StockGen Research. After he learned the reason for it, and that her experiences were in connection, with his new friends, he brought her back into contact with the Turtles, sparking another important friendship for them.
However, Casey's home life remained turbulent, and after his father beat him once again, Splinter declared that Casey would live with them from now on. However, his proximity to the Turtles led to far more serious injuries in the City Fall arc, where he was stabbed in the stomach by Shredder. He was rushed to the hospital by his friends and recovered, but they were forced to leave behind Leonardo to save his life. It was during this period that the growing feelings he had for April became a full-blown relationship.
However, Casey's relationship with his father was irrevocably broken after this event, with his father's return to his old life as Hun, leader of the Purple Dragons, and follower of Shredder. Hun attempted to convince Casey to either leave New York or join up with the Shredder, but when Casey refused to do either, his father attempted to kill him. Fortunately, he was saved by his old friend Angel Bridge.
He accompanied April and the Turtles to Northampton, presenting himself to April's parents as her boyfriend for the first time. They were very accepting of him, and he later accepted an offer to work at the Second Time Around store.
However, neighborhood security patrols brought him into conflict with the Purple Dragons again, as well as bringing a drunken Hun back into contact with Casey. When Hun and the Dragons attacked the Second Time Around store, Casey fought Hun while Angel, Alopex and local residents fought against the Dragons.
Casey and April then went on a road trip to the American Southwest, in search of information about the godlike immortals known as the Pantheon. He was targeted by the Rat King during this time, who preyed on Casey's inner fears and assaulted him with countless rats. He and April also reached a rough patch in their relationship, but promised to work on it.
However, the fears inspired by the Rat King continued to haunt him, as he began desperately trying to overcome any weaknesses in himself. This led to further strain with April, and the two decided to spend some time apart.
He ended up taking counsel from Splinter about what to do, discussing the recent events of their lives, and Splinter suggested that Casey take up the Purple Dragon leadership. However, this did not change his closeness to the Turtles, as he visited them for a Christmas party and was somewhat more warmly reunited with April.