- "I should have known... She didn't like me... Girls never like me."
- —Caboose about Tex
- "Caboose, I don't think anybody likes you."
- "I like me..."
- —Caboose in Human Peer Bonding
One running gag in the series is how Caboose interacts with other characters. Although he tends to annoy a majority of the members of the Blood Gulch Crew, his relationship with them seem mostly positive.
Caboose seems to like all of his teammates with the possible exception of Tucker.
Caboose's most prominent relationship is his remarkable admiration of Church, whom he calls his best friend. After dealing him several initial misfortunes, including inadvertently killing him while driving Sheila (which is later revealed to be Church's host body Jimmy), Caboose was eager to make amends and become Church's friend; his attempts to do so inevitably failed. Even though Church seems to hate him, partially due to killing him, Caboose still has wide-eyed admiration for him and will do anything to please him. In Caboose's Mind, Church is his foul-mouthed best friend, who is later killed by Omega and replaced by Yellow Church for some time. Caboose seems incapable of understanding Church's dislike for him and will often disregard Church's statements of irritation toward him.
Caboose is also incredibly loyal to Church, offering to go in his place to the Freelancer base with Washington. Though this is shot down by Wash, it actually impresses Sarge due to his unthinking willingness to sacrifice himself. For his part, Church puts up with Caboose, but often loses his temper at him. However, over time Church has proven to become nicer and more caring towards Caboose. In Episode 76 for example, Caboose implied that he didn't know how pregnancy occurred, and Church promised to read a book with him. In Episode 98, Church even seemed genuinely distraught when Wyoming and Gary kill Caboose.
At the end of Reconstruction, Epsilon remains in Caboose's possession, which was not Washington's intention, as Caboose was meant to hand over the unit to the authorities but forgot. Caboose treats it as a friend and tells it stories while attempting to build a robot body so Epsilon can be his "new super best friend." Later, he manages to transfer Epsilon into a Forerunner Monitor, gaining the personality of Church. Following this, Caboose and Epsilon's relationship becomes similar to Caboose and Church's relationship, except a bit more friendly.
In Season 10, despite replacing Epsilon with Wash, Caboose retains his friendship with him. However, their friendship is greatly strained when Epsilon blames him and the other Reds and Blues for causing him trouble on a daily basis. Thankfully, in Reckless, Caboose was able to forgive Epsilon, eagerly going with the rest of the gang to rescue him and Carolina. In True Colors, when the two met again, Epsilon was able to help Caboose remember how to get angry and unlock his fearsome fighting skills, implying that he has a fondness for Caboose.
After Epsilon left with Carolina in Season 11, Caboose fell into a deep depression, leading him to discover a Mantis, which he named Freckles. Caboose then used Freckles as a means to cope to with Epsilon's departure, and soon grew a strong attachment towards the robot. Fortunately, after Epsilon and Carolina reunite with the Reds and Blues, Caboose quickly becomes overjoyed by his friend's return.
When Caboose first arrived at Blood Gulch, he didn't have much of a problem with Tucker. He eventually grew to hate him due to his belief that Tucker was vying with him for Church's attention. In Caboose's Mind, Tucker is portrayed as annoying with a simplistic and disgusting state of mind. This is mostly because he sees Tucker as a rival for Church's love. However, Tucker seems to be more tolerant of Caboose than most characters, even showing signs of liking him at times, though most of the time he finds him equally as irritating as Caboose views him to be.
In the episode This One Goes to Eleven, Caboose becomes disappointed at the fact that he rescued Tucker from Epsilon-Tex, further pointing out his dislike for him. It can be noted that Caboose occasionally contradicts himself on his view of Tucker. He states that he never really liked Tucker, but will still show concern for him and call him his 'friend'. In Ready…Aim…, Caboose admits that despite their differences he considers Tucker and himself to be pretty good friends.
After they joined the New Republic, it's shown that Caboose and Tucker now have a brotherly bond and will complement one another, as seen in Thin Ice. In Out of the Frying Pan, when Tucker shows disgust to Epsilon for leaving them, Caboose gives him a speech that they've all made mistakes and that it's best to forgive Epsilon's absence. Shocked and moved by the speech, Tucker follows Caboose's advice.
Caboose first met Sheila when he went to help Tucker and Church. Caboose grows to believe that Sheila is his "girlfriend" and becomes very jealous of Lopez and Sheila's relationship. He even tries to call Sheila back to him by baking her a muffin, as in Nut. Doonut. When the ship containing Sheila was found by Washington, Church, and Caboose in Reconstruction, he asks if she's there. When Washington began ordering the ship to do things, Caboose snaps back "Do not talk to her like that. She is not a program!" with Church nervously backing away saying, "I'm just gonna stand behind Caboose for a few minutes. You know, for safety."
Caboose doesn't interact with Tex a lot in the series, but before actually meeting her, Caboose called her a slut. When Tex first arrived in Blood Gulch, she used Caboose for target practice. He appears to have a fearful respect for her and tries to be polite in his own way. Tex, however, doesn't return the favor and continues to find ways to torment him, like punching him while he's asleep (as referenced in Calm Before the Storm). In a conversation during the end of Season 5, he practiced his way of talking to women with her so he could run a decoy with Sheila. Caboose stated that she was pretty and that he was happy that she hadn't hurt his body in a while.
Caboose seems to like Agent Washington, although becomes slightly scared of him after he kills Agent South. In Caboose's Mind, Washington calls himself "Agent Washing-Tub," acts very secretively, and likes to scare people that are "just trying to help him" (though Church notes that this is actually quite similar to how he acts in the real world). Caboose also believes that Washington fights futuristic aliens and robots with his "Freelancer Powers." However, his negative perception of Washington does not prevent him from contacting him in Catching Up for help nor prevent him from acting friendly towards Washington.
At the end of Revelation, Caboose welcomes Wash into the blue team to keep him from going to prison. In the premiere of Season 10, it's realized Caboose sometimes called Washington "Church" because his new armor color was confusing, and apparently sang happy birthday to him on one occasion. Caboose states in the episode Out of Mind that he thinks of Washington as a friend. Washington also returns the sentiment, as he points his gun at Carolina for aiming at Tucker in Change of Plans and tells her his disliking of people threatening his friends. After Caboose's "promotion" he puts Washington on lookout duty because he considers him "scary".
But later, when Washington has a heart felt talk with him, Caboose tells Freckles to listen to Wash as he is "very smart and really nice," before giving Washington back the position of leader. During the Battle of Crash Site Bravo, Caboose is horrified when Wash is injured and later joins the New Republic in hopes to rescue the captured Blood Gulch Crew members. When they are reunited in Season 12, Caboose is truly happy and states it's "Good to have ya' back, Agent Washingtion!"
He savagely beat the Zealots for injuring Washington in Season 15.
Caboose's only interaction with Sister was when he gave her a tour of the base. In Caboose's mind, Sister is Church's twin-brother who came from the moon.
Caboose seems to take a liking towards Junior. Caboose gave a gallon of blood to Junior and was there when Tucker first saw him, telling Tucker to tell him "how his Dad got to third base with you." Caboose even said that he wanted to scrapbook with Junior.
Caboose and Freckles seem to have a very strong relationship, similar to a boy and his dog. After Caboose repairs Freckles, he immediately takes a liking to him and treats him as his own pet. He is also the only soldier that isn't intimidated by Freckles and seems to greatly care about him. Because he repaired him, Freckles follows Caboose's every command without question, threatening to hurt others in the process to protect him. During his time as the Blue Team "leader", Caboose spent a majority of his time playing with Freckles, which caused Freckles to become a bit more caring and protective of the Blood Gulch soldiers. Caboose later tells Freckles he's "one of the best machines I know. And that is saying something because I have been friends with a lot of machines," in Neighborhood Watch and shows great concern for him in Fire.
When Wash reunited the two (albeit with Freckles in storage chip form), Caboose was overjoyed at his new form and said that his new form was great as Freckles could fit in his pocket and wouldn't try to kill them. Later on, Caboose showed concern when finding out that Freckles' storage chip contained a tracking device, though became relieved after Epsilon removed it. When Freckles is transferred into Caboose's assault rifle, it is shown that Freckles still proceeds to refer to Caboose as "Captain Caboose," showing his respect towards his master (though it should be noted that he was a captain for the new republic).
While the two have technically never met Jimmy was the first victim of Caboose's team killing.
While the two are never seen interacting after Jones untied Caboose he shot Jones in the back.
Like Church, Miller was heavily annoyed by Caboose's stupidity to the point where Miller had Caboose tied up in the brig.
Caboose was teleported to Battle Creek with Sarge and seemed to get along with him, though Sarge did say Caboose made him miss Grif. After the two got out of Battle Creek, Caboose asked if he could "push the button to make [the microphone] go?" Sarge complied and even said, "Heh, what a little rascal," showing some admiration of his innocence, much to Simmons' dislike. Later, Sarge showed respect for Caboose when he asked for Washington to take him instead of Church (encouraging Grif to sacrifice himself as well).
When Caboose was presumed to be dead in My House, From Here, Sarge suggests that he and Grif "have a moment of silence in honor of the dead Blue guy," and commences a prayer - however he does so jokingly. In Caboose's mind, Sarge talks with a pirate accent and, on one occasion, a Cockney accent, admitting himself that he's "not very consistent." Unlike the other characters, Caboose mostly refers to Sarge as "Red Sergeant." Additionally, Caboose does not seem to mind taking orders from Sarge, even though he is on the Red Team, such as in Best Laid Plans and Think You Know Someone.
Caboose hasn't interacted with Simmons very much at first, although he frequently gets his name wrong, calling him "Simmond" and "Simon", while Simmons sees Caboose as an idiot. However, he does manage to say his name correctly in Visiting Hours and in later seasons. Caboose's mental projection of Simmons speaks in a high voice, believes himself to be called "Simon," and is scared very easily. As the series progresses, both begin to treat one another like neighbors, if not friends. This is shown in n+1, where Simmons apologizes to him for his "loss" and in Season 11, where Caboose openly welcomes him to Blue Team when he "joins" it.
Although not much has happened between these two, Caboose once believed his name to be "Gruf", but later learned his real-name. In Valhalla, Grif treats Caboose more like an annoying neighbor than his enemy. In Caboose's mind, Grif is yellow and Simmons calls him "the orangish guy whose name I forget." In Recreation, Caboose misspelled his name as Griff, infuriating the latter. In the Chorus Trilogy, their relationship has improved during their time with the New Republic, though Grif is annoyed by Caboose's stupidity still.
Caboose and Donut seem to get along quite amicably, quickly becoming good friends when Donut is captured by the Blues in Season 2, and they renew this friendship in Recreation, when Donut went to the Blue Base for help. When Caboose first saw Donut, he thought he was a general and gave him their flag and when he was him in his pink armor, he tought Donut was female. In Caboose's Mind, Donut is a female even though Caboose knows Donut. As a running gag between the two characters, Caboose often confuses Donut's name with other types of pastry, calling him "Private Biscuit," "Lieutenant McMuffin," "Admiral Buttercrust," "Commander Poppin Fresh" and "Major Cinnamon Bun" in their first encounter at Blood Gulch.
This is also referenced at the start of Recreation, where Caboose recognizes Donut as "Muffin Man" (although from then on Caboose manages to get Donut's name right). Although they are on different teams, Donut acknowledges their friendship in Episode 38. Surprisingly, Caboose joins the others in attacking Donut in Long Live the King.
Despite having only a little interaction with him, Caboose initially disliked Lopez, due to Sheila's interest in him.
Caboose's view on Project Freelancer varies from the members in it. However, he does acknowledge the abilities they possess.
Caboose seems to acknowledge Wyoming as a threat. When the Blues were taken hostage by Wyoming and Gamma, he came to help his team but was killed in the process. However, Wyoming was forced to use his time distortion to prevent himself from losing, which also "resurrected" Caboose in the process.
Caboose has little interaction with the Meta, only facing him during Reconstruction and later being knocked out by him so the latter could take Delta.
Caboose does not seem to be visibly intimidated by Carolina, and believed that she was pretty under her armor when she threatened to show her "ugly side", which angered her. Although Caboose declines to help her and Epsilon with their revenge in Change of Plans, Caboose becomes depressed on their departure and becomes overjoyed when the Blood Gulch Crew later decide to go save them. While on Chorus, Carolina saved Caboose's live from a space pirate in Crash Site Crashers, showing she has grown fond of him.
Caboose treats the A.I. with respect, even Omega. Also, it should be noted that Caboose has the second highest A.I. count in the series.
Caboose is first infected by Omega (O'Malley) at the end of Season 1, and is most likely the main reason for Caboose's long mental decline. Whilst infected, Caboose had the tendency to periodically say aggressive things in a deep, threatening voice. It is highly possible that the battle between Tex, Church and O'Malley inside Caboose's mind, as well as the A.I.'s subsequent expulsion, damaged his mind, causing him to become more separated from reality.
After the A.I. was ejected from Caboose's mind, Caboose gained the ability to unlock a berserk rage inside himself, stating that "O'Malley taught me to be mean." Caboose has stated that he and O'Malley "were like roommates." Omega, however, does not appear to share this sentiment; when infecting Caboose for the second time in the climax of the Blood Gulch Chronicles, the A.I. states, "Wait - what am I doing inside this idiot!?"
Caboose seems to like Delta and apparently trusts him as Epsilon-Delta states that he "was a trusted source of information" for Caboose. Delta seems not only able to tolerate his stupidity, but also enjoys his company. Caboose was also the only member of the group to willingly implant Delta into his armor during Reconstruction: Chapter 6.
Due to F.I.L.S.S. having the same voice as Sheila, Caboose mistakes her and treats her like Sheila. Although they act decently to one another, F.I.L.S.S. was willing to kill Caboose when they first met (due to her protocol) until Epsilon spoke. It's also shown their relationship is more strained, as when Epsilon-Tex was unleashed and Simmons asked for his aid, Caboose told Simmons "[F.I.L.S.S.] won't let me! She's mean! This place is filled with mean ladies."
In Season 12, Caboose was assigned his own squad when Kimball promoted him to Captain. Although he gets along with the faction, Kimball states that Caboose has officially been forbidden from operating vehicles and heavy machinery for unknown circumstances.
It's shown that Caboose has a decent relationship with his lieutenant, Smith. Smith is blindly loyal to Caboose, as he misinterprets everything the latter says as ingenious, similar to Caboose's loyalty to Church. For example, Smith outright calls Caboose the wisest person he's ever met Teaming with Problems, confusing the other captains. In turn, Caboose is shown to enjoy the praise he obtains from his lieutenant and supports his assumptions.
After Caboose leaves with the other captains, Smith doubted they would return. When Felix lies that the Blood Gulch Crew died, Smith is genuinely upset over his captain's death. This later becomes his motivation to proceed to face the Federal Army of Chorus at Armonia. When the captains and recruits are happily reunited in You Know Who We Are, Caboose expresses his appreciation to the recruits and states his friendship with Smith, much to Smith's joy.
After Kimball made Caboose a captain she immediately recognized his stupidity and banned him from using heavy machines and vehicles.
While the two don't interact much both are noted to be extremely stupid. When Tucker called Palomo a constant source of disappointment it seemed to make Caboose jealous.
Caboose's interactions with the company were minimal before the Chorus Trilogy. After learning of the Space Pirates' involvement in the Chorus Civil War, he greatly dislikes Charon Industries and its members.
After they directly meet each other in My House, From Here, the Insurrection Leader (known as C.T. at the time) was greatly annoyed by Caboose ignoring his directions and stupidity. While Caboose showed no noticable opinion on C.T., C.T.'s anger toward him develop to wanting to kill Caboose on sight for his actions. When C.T. attempts to kidnap Epsilon, Caboose most likely developed a disliking toward him.
When he first met Felix in Season 11, Caboose was surprised that Felix knew who the Reds and Blues were. After joining the New Republic, it's shown that Caboose is often confused about Felix's phrases to describe a situation or object, such as him describing the impossibility to rescue their friends and calling the ancient alien weapons "babies" in Something Else Entirely. Even though Felix humiliates him and the rescue team in Training Daze, Caboose doesn't seem to harbor any negative feelings towards him. However, after the latter betrayed the Blood Gulch Crew in Cloak and Dagger, Caboose loses respect for Felix and sees him as an enemy.
In Motion to Adjourn, Doc rubs Caboose's neck with aloe vera to treat his foot injury. Caboose doesn't seem to mind Doc, though in Season 5, after Doc fed Junior some of Caboose's blood, Caboose tells Church "Don't leave me with the horrible Doctor," terrified of what else Doc would do to him. However, in later seasons, Caboose seems to take a liking to Doc.
Caboose and Andy get along quite well. In Hello, My Name Is Andrew, Caboose tries to explain to the other Blues that Andy had spoken to him but, because Andy did not reply back at that time, the Blues merely thought Caboose was going crazy. Andy took offense to the fact that the others found it difficult to speak to him, thinking that they are the "too good to talk to a bomb" types; this is likely the reason why he befriends Caboose so easily, because Caboose was able to overlook the fact that he is a bomb and speak to him normally.
Andy additionally is not an insensitive, vulgar jerk towards Caboose (as he is towards the others), such as in The Storm and Two for One. In the latter of the two episodes, it is clear that Caboose thinks highly of Andy when (unbeknownst to him) Sarge swaps Andy for Lopez's head; Caboose believes Andy to have turned human and immediately grows excited, but then after Sarge swaps Lopez with a skull, Caboose is heartbroken and cries to Church and Doc about the death of his "second best friend."
When Caboose first met the alien, Caboose told the others that he bit him, but they became friends. Later, Caboose decided he wanted to keep the alien as a pet and wanted to name him "Fluffy, the alien that only loves" or "Crunch Bite." Along with Andy and Tucker, Caboose joined the Alien on its quest before his death.
Caboose and Dr. Grey are shown to get along well. Grey is the one who put Freckles into Caboose's rifle and is one of the few characters who isn't annoyed by Caboose's stupidity. Though she did recognize that Caboose shouldn't be trusted with a gun.