Family and Friends
The Turtles: Slash had a personal vendetta against Leo, Donnie, and Mikey. Since Raph hasn't been able to tell his feelings to his brothers, he has told Spike his feelings about what happened in every problem he has encountered. Because of that, Slash somehow sees Raph's brothers as enemies that need to be wiped out in order for his master to be free. He had almost finished his vendetta too, if Raph hadn't stepped in to stop him. Slash hated Raphael, which caused their friendship to end briefly. Master Splinter knows Spike is Slash. It can be presumed that Slash's disdain for the other turtles ended in Newtralized.
- Raphael: Raph tells Spike his feelings and thoughts because he can't with his brothers. Raphael really cares about Spike because he's always feeding, pampering and watching over Spike, and is overprotective of him when his brothers tease him about Spike. When Spike mutates into Slash, Raphael comes in angry and complaining saying his brothers never understand him. That is when Slash says his brothers never understood him, but he always did. Even though Raphael had to fight Slash in order to save his brothers, he still cares about Slash enough that when the tortoise was falling from the roof, Raphael still reached out to try and save him. Slash still cares about Raphael as well, going to save him from a Kraang sneak attack. Slash encounters Raph again after he has teamed up with the Newtralizer, still a little miffed about their past fight. He and Raphael fight several times, before Raphael saves Slash from nearly getting stepped on by his new pal. Touched that Raphael still cares for him, Slash turns against the Newtralizer and helps the turtles win the fight. Anger no longer boiling between them, Slash and Raphael make amends. Their past fight is forgotten, and Slash decides to set on a journey of his own. In Battle for New York, Raph is very happy to see him. When Slash was Mind controlled and attacked Splinter he was the one (along with Leo) horrified to see this and the two became enemies (briefly) once more. After the worms came out they made amends
- Leonardo: Like the other turtles, Slash wanted to get rid of him while Leonardo was surprised that Spike had mutated. When they encountered his new team "The Mighty Mutanimals", Leonardo still had a strong distrust to him leading to conflict when Kurtzman insisted that they work together to stop the Kraang. Leonardo continued to distrust him until he saw Slash saved Pigeon Pete's life causing him to have a change of heart. In the end, both Slash and Leo bury their conflict and recognize each other as true leaders, shaking their hands in Battle For New York.
Master Splinter: Slash and Splinter don't really interact much but before his mutation Splinter asked him if he wanted to here a story after Raphael's refusal. After his mutation he and Splinter appear to be on good terms at least until the mutant tortoise struck him with his mace and abducted Raphael. Slash later apologize for his forced actions, but Splinter knowing that Shredder was behind the whole thing says there was no need.
Mighty Muntanimals: When they were formed by Jack Kurtzman, the Mutanimals chose Slash as their leader, and it is possible that he taught them ninjutsu in response to this.
- Leatherhead: Slash teamed up with Leatherhead and makes him his second-in-command. In Battle for New York, after the team was captured and Slash was lamenting the situation and called himself unfit to lead; Leatherhead comforted him by mentioning the good Slash has done for other mutants. Touched Slash called the Alligator "Brother" meaning they share a close bond and Slash finally found the brother figure he sought in Leatherhead. In Clash of the Mutanimals, Slash was mind-controlled by Shredder into fighting Leatherhead as the latter stated they were friends until Slash was freed by Dr. Rockwell.
The Kraang: Slash was captured by the Kraang several times, but in the last time, he was freed by Newtralizer and teams up with him to wipe them out. After his change of heart though, Slash plans on breaking the Kraang's rule over the city with the Mutanimals.
- Shredder: Slash and Shredder didn't interact much except when the dishonorable ninja used his Mind Control Worms on him and Rockwall to attack Splinter and abduct Raph, but Slash breaks free of from Shredder's control with the help of the Turtles and the other Mutanimals, then drop a huge statue on the crime lord.
- Tiger Claw: In Clash of the Mutanimals, Slash was recognized by Tiger Claw during their battle at the docks, giving the clue that the two had already met sometime during the Kraang invasion.
Newtralizer: Slash teamed up with him to fight the Kraang. Newtralizer rescued him and became a brother to him. But Slash disagreed with Newtralizer's plan on destroying Manhattan to eliminate the Kraang, so he joined the Turtles side.