HistoryRaphael rescued Spike after he was flushed down a toilet and into the sewers. Spike's favorite food was lettuce leaves and was frequently seen chewing on a leaf. Raphael had a soft spot for Spike and often talked to Spike about the important parts of his life in private. This was important for Raph, as he needed Spike as a sounding board for his inner-thoughts and feelings. He could not reveal his feelings to his brothers because he doesn't want to seem "soft" to them, so he shares them with Spike, who could not speak at the time, but was an excellent listener. His brothers sometimes teased him about this. Raph often played with Spike and cooed at him, as well as allowing Spike to ride around on his shoulder, frequently using his pet for personification.
In Season 2 episode 7 Slash and Destroy, Spike mutates into Slash and tries to kill each of the Turtles. At first, when Raph discovers that Spike mutated from the mutagen, Slash suggests that they work together (without the others), which Raph agrees sounds good. However, he reconsiders matters when Slash starts attacking the others and collecting their bandannas. Raphael ultimately defeats Slash by pressing a pressure point on his arm. As Slash begins to fall off of a building ledge, Raph attempts to save him, but is too late and he falls off of the building and crashes on the sidewalk. Raph then looks away, but when he looks back, he finds that Slash is gone.
His next appearance is in Metalhead Rewired as one of the detained mutants in the Kraang prison. He is seen threatening one of the Kraang droids shortly before a mind control chip is planted on his forehead, putting him to sleep. After Metalhead frees all of the mutants, Slash proceeds to destroy a large number of the Kraang droids, including one that was about to shoot Raphael. He then nods at Raphael and makes for the portal.
In Newtralized!, Slash returns and teams up with the Newtralizer. They destroyed a lot of Kraang bots and left their remains in pieces. Raph and Casey was shocked to see the Kraang bots completely destroyed on the spot. Later, Slash sees Raph and Casey from the rooftops and heads after them. He drops in to see them and wondered if Raph missed him. Casey questioned Raph about Spike being mutated and naming himself Slash. Slash reveals to them about his new partner the Newtralizer, who was busy blasting the Kraang on the side. Slash told Raph and Casey to keep out of the way while they fight the Kraang bots. The Newtralizer retrieved the teleportation device and infused it with plutonium. He gave one to Slash and they quickly escaped. It was revealed that Slash had teamed up with the Newtralizer sometime ago, where the Kraang captured Slash. The Newtralizer quickly dispatched those Kraang bots and Slash made an alliance with him. The Newtralizer and Slash argued about using a Kraang device called the "Kraang Walker" to destroy the Kraang and possibly humans. Slash did not like this and the Newtralizer stated that he would go to extremes no matter what. When they arrived at the docks, the Newtralizer told Slash to distract the Kraang bots while he goes after the Walker. After the Newtralizer obtained the Walker, he almost stepped on Slash but Raphael saved Slash just in time. Slash was surprised at Raphael for saving him and Slash went to confront the Newtralizer on the Walker. Slash argued that the turtles helped them fight the Kraang and the Newtralizer did not care. Slash used his club weapon to trap the Newtralzier in the Walker. Before the Newtralizer could shoot Slash, Raphael threw a shuriken at the Newtralizers' weapon. Slash, Raphael and the other turtles tried to escape from the Newtralizer. Suddenly, Casey showed up and helped the turtles in fighting the Newtralizer. Casey was able to get one of his hockey puck detonators into the Walker and destroyed it. The Newtralizer escaped and Slash told Raphael he is better off solo. Slash said his goodbyes to the turtles and Casey before leaving.
Slash, both unmutated and mutated, shows a great deal of love and loyalty to Raphael. Naturally, since he had been with Raph for years, he silently observed Raph and his family and listened to all of Raph's problems. Once he mutates, he becomes obsessed with removing anything he deems to be holding Raphael back, including the latter's family. Slash is even willing to harm Raph himself to prove that he needs to let go of his more positive qualities so that he may become a "true warrior". Ultimately, while Slash is a crime fighter, he possesses no kindness and seeks to turn Raphael into a relentless killing machine like himself.
However in Newtralized!, Slash was shown to go against killing innocents (and those that assist him) to justify the means, unlike the Newtralizer. He later makes amends with Raphael and helps take down his former partner with the rest of the team. He then leaves on a positive note, preferably to work alone for the time being. In Battle for New York, Slash reveals that his violent and deranged behavior before was due to the effects of the mutagen affecting his psyche and was clearly mournful about his past actions.
- "They never understood ya...Not like me."
- "Tell 'em you got a new partner, one who knows the true meaning of being a warrior."
- "You and me. No joking around. No goofing off like your brothers. We'll be the ultimate ninja team."
- "We'll crush our opponents. We'll fight evil together."
- "Ha, never liked the name Spike. Call me...Slash."
- "If Raph is gonna be free, we may need to lose some dead weight. Hahaha."
- "Yep, we'll right the wrongs of the world. And we'll wipe out whoever stands in our way."
- "That's right Raph. We're not like the others. They're weak, but we're powerful. Our anger makes us strong."
- "It's over, Raphael. You lost."
- "Been looking forward to that for a long time."
- "I'm not here to fight you."
- "A true warrior's spirit. We're the same you and me."
- "Heh, heh, heh. My turn."
- "Keep me prisoner? HAAAAAAAH!"
- "I'm gonna rip, every tentacle off ya!"
- "It's Slash now, remember. Good to see you again Raphael, miss me?
- "We're taking care of the Kraang. I got a new partner now."
- "What you Turtles couldn't, whipping out the Kraang. Keep out of the way!!!"
- "Blow this place? Too dangerous. What about the humans out on the street?"
- "I owe you one. The name's Slash."
- "I'm with you brother. Destroy the Kraang at any cost."
- "Eager for another beatdown Donatello?!"
- "...I'm here to take out Kraang, not people!"
- "And I'm suppose to trust you inside that thing?!"
- "You're no brother of mine!"
- "I need to go my own way Raphael. Think I'm better off solo."
- "Goodbye brother. I'll see you all again, someday..."
- Slash is voiced by Corey Feldman, who previously voiced Donatello in Teenage Mutant Ninja Turtles (film) and Teenage Mutant Ninja Turtles III. Feldman also co-starred with Sean Astin (who voices Raphael) in the 1985 movie The Goonies.
- Slash's belt buckle is actually a hood ornament from an old car.
- The creators have said that he may become an ally later on.
- This is hinted at in Newtralized! as in the end Slash leaves on good terms with the turtles (though he still prefers to be solo).
- Slash can impersonate Leonardo.
- Slash is one of the hardest enemies to defeat, mainly because of his super strength and knowledge of all of Raphael's moves.
- Slash is a ruthless fighter, but has a sense of honor in that he will not harm innocents and civilians.
- Slash's skin color is the same as his 80s action figure.
- After his mutation, Slash resembles an Alligator snapping turtle.