The Beast Within is the 35th episode of the Teen Titans series and the ninth in the third season.
Inside an animal testing laboratory, the Teen Titans fight Adonis. The battle-suited villain easily defeats four of the Titans, but enrages Beast Boy to the point where the latter literally cuts loose and attacks Adonis furiously. During their fight, they puncture a tank containing strange chemicals and get drenched by them. After Adonis is beaten, Beast Boy exits the lab in an extremely aggressive mood, leaving the other Titans bewildered.The next morning, Beast Boy begins to display very untypical behavior, even for him: He suddenly develops an appetite for meat, becomes downright rude and aggressive, and under stress even turns into his animal forms more frequently. When he finally feels unjustly provoked by Raven, he attempts to attack her, but is stopped and rebuked by the others, who are put off by his manners of late. In a rage, Beast Boy walks away angrily to his quarters, smashing up his furniture, and suddenly transforms into a huge hulking monster. Raven, passing by his room, hears a strange sound, but as she attempts to see what is going on, a monster comes out and attacks her. Upon hearing her fearful cry, Robin, Starfire and Cyborg rally, but they find Beast Boy and Raven missing and Beast Boy's quarters devastated by claw marks. Following Raven's tracer, they find her in the sewers hanging unconscious and injured from the fangs of a big green werewolf monster. The creature proves a very tough opponent to fight, and only with the greatest effort do the Titans manage to subdue it - to find out to their immense surprise that the creature was none other than Beast Boy!
In the Tower's sickbay, Cyborg notices upon analysis that a strange genetic compound has mingled with Beast Boy's DNA. Distraught by Raven's condition and the fear that he is the one responsible, and stressed by Robin's forceful questioning, Beast Boy transforms into the werebeast yet again and immediately goes after Raven. The Titans drive him away and back into the city; Robin and Cyborg take up pursuit, while Starfire stays behind to take care of Raven. Some time later, Raven comes to, but she testifies that Beast Boy had not attacked, but saved her.Robin and Cyborg follow Beast Boy back into the sewers - to encounter actually two werebeasts brutally fighting each other. After a long and arduous struggle, Beast Boy manages to subdue his opponent, who turns back into his true self upon losing consciousness: Adonis. After the strange compound is identified as the cause and an antidote administered, Beast Boy sits on the Tower island's shore, where he is joined by Raven. While Beast Boy is still fearful about this animalistic self lurking deep inside him, Raven gently assures him that knowing when to let this bestial side out makes him all the more human. Feeling more mature now, Beast Boy considers a change of name, spoiling the tender moment.
- It's a likely possibility that in the sickbay/infirmary, Beast Boy (as the Beast) was in a rush to check up on Raven (which the others misinterpreted as intent to harm/attack). When he sniffed her and a look of anger crossed his face, there's a chance he looked angry because he knew she was hurt and he got angry at Adonis. That may be the reason he escaped the infirmary: to go after Adonis.
- The animals that Beast Boy turned into in this episode is a wolf, a bull, a baboon, a tiger, a Bigfoot/Sasquatch, a rhinoceros, an Ankylosaurus, a lion, a bear, and even a Werebeast.
- Beast Boy was mad at Raven because she makes fun of him, insults him, and saying his sentence is a bad grammar (while he was facing Adonis).
- We've learned that Starfire's favorite show is "World of Fungus".
- Beast Boy still used his Werebeast form in The End pt. 1.
- Beast Boy ate meat for the first time.
Beast Boy: I think my appendix and my spleen just switched places. Adonis: You wimps think you can take down Adonis? Bring it on! Beast Boy: Dude, it is totally brunged! Branged! Raven: Ooh, bad grammar. That oughta scare him. (Beast Boy gets annoyed) Robin: Titans, go!
- Adonis: What's the matter, wimp? Don't you know how to fight like a man? Beast Boy: I'm not a man, I'm an animal! (continues to fight Adonis)
- Beast Boy: So, he was the one who hurt you, right? Not me? Raven: He broke into the tower to attack you. And wound up attacking me to. Beast Boy: Ugh!!! I can't believe I ate meat. I acted like a jerk. I'm sorry. Raven: You weren't yourself. Beast Boy: Cyborg says the chemicals at the lab messed with my DNA. Unleashed something primal. Raven: And he gave you an antidote. You're better now. Beast Boy: Yeah. But that thing, that beast, it came from inside me. And it's still there. I can feel it. Raven: Good. If it wasn't for that beast, I might not be here right now. Having that thing inside doesn't make you an animal. Knowing when to let it out is what makes you a man. Beast Boy: Hmm. Maybe you should call me...Beast Man from now on. Raven: We're having a moment here. Don't ruin it. Beast Boy: Beast Dude? (Raven sighs)
- Cyborg: (the Titans are at the sickbay. Raven is seen floating above the bed in a healing trance) She's alive, but she's in some kind of trance. Robin: She's healing herself. Beast Boy: And you're telling me I did that to her? That's impossible! Robin: We found you with her. Beast Boy: NO! I wouldn't! I mean, we had a fight, but I would never! Starfire: She was in your teeth. Beast Boy: THAT'S A LIE!! Robin: (walks up to Beast Boy) I'm going to ask you to keep your voice down! Beast Boy: (staring angrily at Robin for a few seconds then softens up) What's happening to me? Cyborg: (scanning Beast Boy's DNA on the computer) I'm picking up traces of recombinant DNA. It's not human. Robin: The chemicals at the lab? Cyborg: Because of the shape-shifting, his genetic code was always unstable. Maybe he's just finally falling apart. Beast Boy: (worried about Raven) Raven. She's gonna be alright isn't she? I mean, she's not moving. What have I done? Robin: You need to tell me what happened. Beast Boy: I told you, I don't remember any of it. We had an argument, I went to my room, I was angry, and then nothing. Claws. A scream. Nothing. Robin: Claws and a scream isn't nothing. What else? Beast Boy: That's all! Robin: No, it isn't! You have to focus! Beast Boy: I am! Robin: You have to remember! Beast Boy: I'm trying! Robin: Try harder! If you can't tell me what happened, I have to assume the worst! I have to put you in jail! You need to remember! Beast Boy: I CAN'T!!!! (his heart monitor beeps like crazy) Starfire: Beast Boy! (tries to go over to Beast Boy) Robin: (hold his hand out) No! Beast Boy: (changing) Get away from me! Starfire: What is... (Beast Boy then turns into a werebeast, shocking the other Titans. Beast Boy in his werebeast form sees Raven floating above the bed and begins to run up to her)
- Cyborg: (while punching Adonis) Come on, big man! Show me what you've got! Show me what you've got! (Adonis grabs him) Well, ok then. (he gets thrown to a wall) Adonis: Nobody out muscles Adonis! Beast Boy: Oh, yeah? Well, my muscles may be small and ropey, but they're not! I mean.... (Adonis attacks and fights Beast Boy)
- Starfire: (gasps) Robin: Beast Boy, careful! The chemicals! (Beast Boy pushes Adonis against one of the tanks containing the chemicals and gets drenched by them in his grizzly bear form. He then repeatedly slashes Adonis until his suit falls apart and Adonis fall out of his suit unconcious. Beast Boy reverts back to his original form and starts to act and talk tough.) Beast Boy: (angry) Who's the tough guy, now? (turns around and begins to leave) Robin: Umm... Good job? Cyborg: Nice intensity. Raven: Yeah. Have any good freak-outs lately? Beast Boy: (angrily turns to Raven) I just got sick of being pushed around. (Turns and leaves. As he walks out of the lab, the caged animals become scared of Beast Boy. The other Titans just stand and watch Beast Boy leave in confusion)
- Raven: (Adonis pins her to the ground) Let me go! Adonis: (Purrs) You're feisty.
- Raven: (wakes up from her healing trance) Beast Boy... Starfire: Rest. You are safe. He can no longer harm you. Raven: He didn't hurt me, he saved me. Starfire: From what?
- Raven: (hearing the strange sound outside of her door) Who's there? (walks up to Beast Boy's room) Beast Boy? (before she can enter, four punches punched the door out of Beast Boy's room. Then a monster comes out of the room as Raven backs away a little. The monster then turns, sees Raven and attacks her.)
- Raven: (Beast Boy bumps into Raven and drops her book. Raven picks up the book and turns to Beast Boy) Sorry. Beast Boy: (angry) You'd better be. Why don't you look where you're going? Raven: On second thought, I'm not sorry and you're a jerk. Beast Boy: (stands angrily in front of Raven) You know Raven, I've been a really nice guy for a really long time. I've put up with your insults, your attitude, and I've had it! Consider this as a warning. As of last night, Mr. Nice Guy has left the building. Raven: (angry) Is this the part where I'm supposed to be intimidated? Beast Boy: (angry) No, THIS IS! (turns into a sasquatch and begins to battle with Raven) Robin: (seeing Beast Boy and Raven fighting shows up with Cyborg and Starfire to stop the fight) BEAST BOY! Leave her alone! Cyborg: What's gotten into you, man? Starfire: You are behaving like a Royal Zargnarf! Beast Boy: (turns back into his regular form and walks up to the other titans angrily) Look, this is who I am now! You guys don't like it? Tough! Robin: Fine! If this is how you want to act, do it somewhere else! None of us are interested! Beast Boy: (he angrily attempts to battle with Robin, but stops immediately) Hmph! That's what I thought. (then he leaves)
- Cyborg: (sees Raven unconsious and injured in the teeth of a werebeast monster) Raven! Starfire: (gasps) (the werebeast puts Raven down safely on the floor) Robin: Attack! (Cyborg and Robin fight off the werebeast while Starfire flies over to Raven to see if she's ok. The werebeast knocks out both Cyborg and Robin and sees Starfire kneeling next to Raven. It runs up to attack Starfire but was knocked away by Robin. Cyborg jumps onto it but it throws him off. It then charges to attack Starfire; however, she turns around and shoot starbolts at it. It then jumps onto her and attempts to devour her. But Starfire kicks it in the face and continues to shoot starbolts at it. The Titans combined their attacks on the werebeast and weakened it. When the smoke clears, the monster turns out to be none other than Beast Boy) Starfire: (gasps) Robin: No. Beast Boy: (wakes up) Where am I? (he looks up and sees the Titans staring at him in disbelief) Why is everybody looking at me like that?
- Robin: (after Beast Boy defeats the other werebeast in his werebeast form, he reverts himself back to his original form while the unconcious werebeast reverts back too. Robin and Cyborg finds the exhausted Beast Boy and run up to him.) Beast Boy! (Robin then walks up to see the other werebeast which turns out to be Adonis.) Adonis. (It was then that Robin and Cyborg came to realize that Beast Boy wasn't intentionally hurting Raven, but he was actually saving her life the whole time. And they even came to realize that Adonis was the one who attacked her, not Beast Boy.)
- Raven: AAAAAHHHHH!!!!!!! Robin: Raven! (runs up to Raven's room) Cyborg: (walks out of Raven's room) She's not in her room. Starfire: Beast Boy? (the Titans run up to Beast Boy's room only to find it destroyed and claw marks are everywhere) Robin: What happened? (they walk up to Beast Boy's broken window and find claw marks on the side of the tower. They then go to Jump City to do a search and rescue for Raven and Beast Boy) Alright, team. We got two Titans missing and no explaination. We need answers, so split up!
- Starfire: (sees a shadowy figure with claws and speaks through Titans communicator) I have spotted something. Something with claws. Cyborg: (through communicator) Staring into your coordinates. Robin: Track it, Starfire. We'll be there as soon as we can. (finds part of Raven's cloak on a bar fence) Raven.
- Robin: (he and Cyborg finally manage to corner Beast Boy) Don't move! Cyborg: (Beast Boy growls and roars continuously) Just chill, man! It doesn't have to go down like this! (Beast Boy walks slowly to them as Cyborg and Robin pose to attack) Robin: When I move, hit him with everything you've got. (Unknown to them, a brown werebeast creeps up behind them. Beast Boy notices him and jumps up to attack the brown werebeast) Now! (before they could attack, the werebeast pounces on Cyborg and Robin, knocking them down. They look up and see Beast Boy and the other werebeast fighting) Cyborg: There's two of these things?! (the two werebeasts continue their fight)