These are Ratchet's relationships.
Of all the Autobots to ever be stationed on Earth, Ratchet is the closest to Optimus, one could also say both of them might be closer then friends. He values Optimus as a worthy leader and believed him to be wise and powerful, even once downgrading several Cybertronian artifacts designed to enhance power useless for Optimus. When Optimus became infected with Cybonic plague, Ratchet was determined in ensuring Optimus gets better and cured him when Bumblebee and Arcee returned from the Decepticon warship with the formula for the cure. However, though the two are great friends, they have had their differences. During Ratchet's first and only time using the Synthetic Energon, he became angry with Optimus for chasing after what he believed were Megatron's small efforts and instead not pursuing his larger projects. During this short argument, he criticized Optimus for being soft and for not killing Megatron when he had the chance. The two rekindled their friendship following the Autobot's rescue of Ratchet. After Optimus lost his memories (after he sacrificed the Matrix of Leadership's energy to destroy Unicron's spark) and was taken to the Nemesis with Megatron, Ratchet worked with the Autobots in retrieving their leader back. With some information about the Decepticons' space bridge, courtesy of Starscream, the team was able to restore Optimus Prime to his normal self and bring him back to the base where Ratchet told Optimus it seemed like it was their darkest hour but through it all, Optimus was a true Autobot inside and out. In Darkest Hour, Ratchet was shocked to learn that Optimus destroyed the Omega Lock on Cybertron and was in deep sorrow to tell him that the Autobots needed the Omega Lock since it was the only way of restoring Cybertron. Ratchet was the last Autobot to talk to Optimus when the team had to separate to avoid getting captured. Before leaving, Ratchet stated that he never thought it would end this way and Optimus replied neither did him when Ratchet had left before the destruction of the Autobots's base. Rafael managed to locate Ratchet and tried to tell him not to give up. Ratchet argued that even with resources, like the Harbinger, it won't be of much use not without someone to lead them. Ratchet showed up later to help Bumblebee and Raf with the Harbinger's systems. Ratchet was able to contact Agent Fowler without any Decepticons tracing their conversation. Suddenly a ship came with Ultra Magnus, the rest of the Autobot team, the kids and later Agent Fowler with Jack's mother. The only ones that weren't there was Smokescreen and Optimus. Ratchet informed them that only Optimus knows Smokescreen's location and that Optimus remained behind to ensure that everyone made it to safety. Ultra Magnus advised they must stop Megatron with or without Optimus. While the team takes on the Decepticon citadel, they ended up being captured. All of a sudden something was flying towards the citadel. Back at the Harbinger, Ratchet picked up the signal to be an Autobot's signal in airborne. It was Optimus Prime in his new body and flying with his jet pack. After the Autobots and Decepticons retreated from the collapsed citadel, the Autobots returned to a new base where Agent Fowler commended them for their efforts in battle.
Ratchet shows Optimus his work on the Synthetic Energon formula in hopes of replacing energon lost in their old base's destruction. Later on Ratchet picks up Decepticon activity and Optimus informs the team with their energon reserves at a critical low they can not afford not to investigate. Though this investigation becomes out of hand when Ultra Magnus and Wheeljack discovers Shockwave's laboratory with the Predacon clones. The pair destroyed the lab, only to encounter Predaking, the original Predacon that Megatron sent to hunt the Autobots. They were attacked by Predaking and were about to be terminated. Optimus came just in time and saved the pair from certain death. Ratchet worked on Ultra Magnus's right hand, which was damaged by Predaking. Optimus explains to Ultra Magnus that Family is greater than an army. Sometime later Ratchet replaced Ultra Magnus's broked hand with a claw, which prevented Ultra Magnus from going on the first mission until Wheeljack helped him. The team managed to capture Soundwave and bring him back for interrogation. Though this was unsuccessful. Laserbeak found their base while the rest of the team went on their second mission in Antarctica. Smokescreen shot a piece off Laserbeak, but failed to stop it from going to Soundwave. Soundwave disabled Smokescreen, Bulkhead and Agent Fowler to advance on Ratchet.
Optimus followed Chip, a drone made by Raf and Wheeljack using Laserbeak's transponder, to the Decepticon warship in hopes of finding Ratchet. He encountered Starscream and managed to destroy his seeker armada, but Starscream found the probe and blew it up. Ratchet tried to escape from the Decepticons but in his efforts provided them the answer to the Synthetic Energon formula for the Omega Lock 2.0. Predaking beats up Ratchet, but Ratchet informed him that Megatron wanted his fellow Predacons terminated. This resulted in Predaking going on a rampage through the ship, which Ratchet took the advantage to contact the Autobots. He informed them that Megatron is planning to use the Omega Lock to cyberform Earth. The Autobots prepare their weapons and went for what it seems to be their last battle. Optimus told them it's an honor to serve with his team and his human friends. As the battle continued it's way towards the Omega Lock on the lower deck of the warship, Smokescreen was able to get the Star Saber. Ratchet told Optimus that he must use the Saber to destroy the Omega Lock in hopes of saving Earth. Bumblebee was shot and killed by Megatron before he could give Optimus the Star Saber. Though Bumblebee was revived by the Omega Lock's cybermatter and killed Megatron with the Star Saber. After the team used the Omega Lock's energy for Cybertron's core, Optimus tells them that with Cybertron capable of supporting life they must return home, though they will miss their human friends/family. Ratchet remained behind to stay with the humans. Optimus gave Ratchet a farewell handshake before leaving to Cybertron. In the ending in Predacons Rising, Ratchet was shocked that Optimus was going to sacrifice himself to restore Cybertron, as he states to Optimus that he did not return to save a life only to lose Optimus, the one who he deeply cares about the most. Ratchet and the other Autobots watched as Optimus fly into Cybertron's Well of AllSparks and restore the planet.
Ratchet is Optimus's closest friend, in fact their relationship could be perceived as more than friends.
Even though Ultra Magnus pressured him on the synthetic energon experiment, Ratchet was able to scavenge parts to repair Ultra Magnus's damaged right hand with a claw. When Ratchet was captured by the Decepticons, Ultra Magnus worked with the team to ensure that they find him. Even Magnus stated to the team that Ratchet may thought that his new hand wasn't good enough, though what truly isn't good enough was giving up. During the ending of the series finale, Ultra Magnus left with the rest of the team back to Cybertron, which was restored, while Ratchet remained behind on Earth with their human friends. In Predacons Rising, Ratchet was called by the Autobots to help take care of an injured Ultra Magnus, who was attacked by two Predacons along with Smokescreen. Ratchet spent most of the time looking after Ultra Magnus while the other Autobots faced Unicron and his army of undead Predacons.
Magnus is like a brother to Ratchet.
Of all Ratchet's medical patients, he considers Bumblebee his greatest mistake, due to his failure to repair the latter's voice box back on Cybertron. He was, however, successful in repairing his body and making him capable of fighting again. After Bumblebee was revived by the Cybermatter and killed Megatron, Bumblebee hugged Ratchet when he realized that he can talk again. Optimus then stated that Ratchet's medical treatments for Bumblebee has pulled through, stating that "It would seem that the old field medic made good after all."
Bumblebee is like a son to Ratchet.
Arcee is rarely seen talking and hanging with Ratchet about some things. When Ratchet discovered some dark energon on Arcee's hand, he scrapped it off and told her to take a decontamination bath to avoid any trouble. When Ratchet used the incompleted Synthetic Energon formula in Stronger, Faster, he clicked at Arcee and asked her "How's it hummin?", which left her disturbed. When Ratchet mentioned Cliffjumper being dead, Arcee was enraged and almost jumped at him. Later, the team rescued Ratchet from Knock Out. Despite mentioning Cliffjumper, Ratchet and Arcee have made amends and Arcee sees him as a great friend on the team. Arcee told Ratchet about Smokescreen saving Optimus from certain death after the destruction of their former base.
Arcee respects and cares Ratchet and would hang out with him like she with the others.
Since Ratchet appears older than Arcee, she appears like a daughter to him.
Out of all the Autobots, Ratchet wasn't too fond of Wheeljack at first. Ratchet stated there was limited space on the team in Loose Cannons when Optimus invited Wheeljack to stay on Earth. In Triage, Optimus paired Ratchet with Wheeljack to go hunt for the Iacon relic. Ratchet stated to Optimus that Wheeljack was a "ruffian" and that Wheeljack was Bulkhead's partner. Optimus stated to Ratchet that he should welcome this temporary alliance. Ratchet left with Wheeljack in the Jackhammer where they made little conversation. Later after Soundwave left with the relic, Ratchet helped Wheeljack up when he was beaten by Soundwave. When they came back to the Jackhammer, Ratchet thanked Wheeljack for backing him up and Wheeljack said goodbye to Ratchet. Wheeljack referred to Ratchet as his real name and not calling him "Doc". In Hurt, Wheeljack told Ratchet that he's a maestro at curing bots after Bulkhead was injured in battle. In Minus One, Wheeljack convinced Ratchet to let Ultra Magnus go on a mission with the other Autobots to the Antarctica. In Persuasion, Wheeljack joined the other Autobots in an attempt to rescue Ratchet from the Decepticons, which it turned out to be a final showdown with the Decepticons.
Wheeljack seems to be a good terms with Ratchet. Ratchet would find Wheeljack's actions bothersome at times, but they both care for each other as teammates and comrades.
Ratchet has a dislike for Bulkhead's constant and often noisy advances in human technology. Ratchet's inventions and equipment is often subject to being broken by Bulkhead, often causing him to utter out his phrase "I needed that" on the objects. Despite these differences, Ratchet was devastated to see Bulkhead in critical condition following his first and only battle with Hardshell during the Autobot's attempt to get one of the four relics. He was also hampered to announce Bulkhead's slow recovery, and he was fearful while stating he may never be fully functional again. In an act of caring Ratchet was not easily phased by Bulkhead's plea to allow him out shortly after his first major recovery from the battle. However, Ratchet allowed him to and Bulkhead slowly started to return to his normal self again. In Persuasion, Bulkhead joined the Autobots in an attempt to rescue Ratchet from the Decepticons, which turned out to be their final battle with the Decepticons.
Bulkhead, in a way, acts like a son to Ratchet.
Ratchet and June seem to have a good relationship, as they are both medical experts, June even greeting Ratchet once and addressing him as doctor. Ratchet in turn gives June respect as a nurse and adult, since he often deals with the kids as well.
Initially, Ratchet regarded Raf as just another nuisance, underestimating Raf's computer/technical know-how because of his age. But he eventually recognized Raf's skills to the point where Raf wordlessly became Ratchet's technical support, and the young boy's close bond with Bumblebee and kind-hearted yet determined demeanor touched Ratchet's spark.
After Raf was seriously injured by Megatron's Weaponized Dark Energon, June was brought in to aid him since Ratchet never had the chance to learn about Human biology and medicine; Ratchet was in deep despair blaming himself for being unable to help as well as being so heavily focused on Cybertron, where he admitted to Optimus that "[he has] grown to need him..." Ratchet ultimately managed to cure Raf's illness with the use of Energon sent into his bloodstream which destroyed the Dark Energon within him. Ratchet was relieved to see Raf recovered.
In Operation: Bumblebee, Part 1, when Bumblebee was left unable to transform, Ratchet volunteered to pick up Raf from school. He even asked Raf is he wanted to ride with siren on and Raf kindly rejected his offer.
They work together on a virus to upload the Decepticon's database on the Iacon relics, after seeing the success, happily led Ratchet to compliment Raf as a genius. After the destruction of the Autobot's old base, Ratchet was in deep despair over their lack of resources. Though Raf mentioned that they could use the Harbinger, Ratchet said resources won't be of much use not without someone to lead them. Later, Ratchet helped Raf and Bumblebee fix the Harbinger's systems. Lately, it has been revealed that Ratchet has spent some of his free time teaching Raf how to read Cybertronian Code. After the Autobots achieved victory and restored Cybertron Ratchet remained behind at Unit:E stating "I know where I am needed" and works alongside Raf and the others.
Ratchet acts as a father figure to Raf.
Although Ratchet originally considered Jack as an annoyance, he soon comes to consider Jack a friend who can be trusted, particularly when Jack is the most responsible of the kids, and he even states Jack is a lot like Optimus before the latter became a Prime.
Miko is often a constant headache for Ratchet because of her reckless behavior. Even so, he's concerned for her safety and her feelings, such as when she was afraid for Bulkhead's life in T.M.I. and in Hurt. Miko cares for Ratchet as well and hangs with him at the base.
Like the other Autobots, minus Optimus, Ratchet was wary of Smokescreen when they first met. The rookie's stories of being at the Hall of Records with Alpha Trion caused Ratchet to think he was a handmade trap Optimus would not be able to resist. After Smokescreen saved Arcee, Bumblebee and Optimus, Ratchet was convinced he was a true Autobot. Later, like the rest of Team Prime, Ratchet was very annoyed at Smokescreen's independence and lack of concern for maintaining their cover. He was shocked to find that Smokescreen had taken Jack on a relic hunt. However, he seemed to care for him as he tried to open several groundbridges for him, when he was trapped on the Nemesis, and showed sorrow when he believed Smokescreen had died. After their base was destroyed, he was curious of the possible link between Smokescreen going back and Optimus surviving. Ratchet commended Smokescreen for saving Optimus's life in Rebellion. Ratchet was curious when Smokescreen said something regarding a Prime in Project Predacon.
Like all the other Autobots, Ratchet views Megatron as a truly evil and vicious tyrant, he is also extremely cautious of the others during their encounters with him. Of all the Autobot's stationed on Earth, Ratchet has had the least amount of encounters with him.
During Megatron's first attempted use of Dark Energon, where the latter called Ratchet "Optimus' Trusty Watch dog". He was eagerly quick to talk trash to the Decepticon leader, even urging him to come off of the pillar he was standing on and engage him. Ratchet even attempted to fight Megatron while on Synthetic Energon. He referred himself as Megatron's "doctor of doom" as he was able to punch the Decepticon leader against a wall but was soon taken down and later saved by the Autobots. Megatron used Ratchet's "doctor of doom" phrase as he manipulated Orion Pax into believing Ratchet and the Autobots were evil but Orion Pax soon discovered through Megatron's deception and realized his place was with the Autobots. When Ratchet was captured, he refused to cooperate with Megatron, even noting the numerous acts Megatron had committed, even crushing Bumblebee's voice box. However Ratchet reluctantly agreed to work on the Synthetic Energon in order to restore Cybertron and once it was completed, Megatron handed him over to Predaking for a serious beating, this act most likely strengthened Ratchet's hatred for Megatron even more as he told Predaking that Megatron let the Autobots destroy Predaking's fellow Predacons.
However, after the events in Predacons Rising, Ratchet may have forgiven Megatron's old past actions.
Soundwave is one of Ratchet's enemies. Ratchet did not come in contact with Soundwave until Triage. In this episode, Ratchet and Wheeljack were on a mission to retrieve a relic when Soundwave followed them. Wheeljack managed to blast Soundwave's pet, Laserbeak, out of the sky but they were shot out of the sky themselves. While Ratchet remained to place his plan into Laserbeak with the aid of Raf over his comm, Wheeljack went to face Soundwave alone. However, Ratchet soon received a warning from Wheeljack that Soundwave was coming to get Laserbeak. Ratchet hid behind a giant boulder to avoid detection from Soundwave as the download was completed. Soundwave retrieved Laserbeak and deployed his tentacles to search for Laserbeak's broken part. The part was near Ratchet's foot, where he was hiding. One tentacle went around the rock while the other was near Ratchet's shoulder. The tentacle retrieved the part and Ratchet was safe. In the ending of Minus One, Soundwave had dispatched Bulkhead, Smokescreen, and Agent Fowler before kidnapping Ratchet.
Ratchet studied Shockwave's experiments back on Cybertron, most notably the Cortical Psychic patch. The two finally met during when Ratchet was captured and brought aboard the Nemesis. As the two worked together on finalizing the Cyber matter, they expressed a mutual respect for each other and in their work. Despite this, they fought during the final battle of the Omega Lock with Shockwave gaining the upper hand in the fight.
Shockwave is almost like a darker version of Ratchet.