In the games, Sir Meta Knight is commonly seen as Kirby's rival, but his true relationship with Kirby is a mystery. The anime does however reveal more about the two's relationship. Sir Meta Knight is King Dedede's loyal servant. Though he says he is loyal to the king, he purposely helps Kirby in secret. The true reason why he serves the king is becasue he knows Dedede has a Holy Nightmare delivery system and likes to order demon beasts. Normally a Star Warrior's Starship automatically goes to places where demon beasts are, so a Star Warrior coming to Popstar was likely. Sir Meta Knight knows Dedede is a stupid king, however sometimes agrees with the king's stupid ideas to help Kirby with his training. Sir Meta Knight and Kirby share the same destiny. They're both Star Warriors. Somehow Sir Meta Knight knows almost everything about Kirby and how he knows remains unknown.
At first of the anime, Sir Meta Knight's thoughts of Kirby was not certain until later on. The fact in the beginning he does name the pink ball "Kirby-dono" implies he at least knowledges Kirby isn't a enemy but a ally. The confirmation of Sir Meta Knight being a Star Warrior just like Kirby was told early in the series. Due to the fact Kirby is still a baby, Sir Meta Knight watches and trains Kirby as he sees necessary. Sir Meta Knight's training can be harsh, but only does it to make Kirby understand the toughness of battle. Though it sometimes appears Sir Meta Knight may push Kirby too hard, but he does worry about Kirby's safety. If he suspects something looks like it may be too dangerous, Sir Meta Knight somehow warns Kirby and may advise to avoid the situation altogether if possible. If things do get bad, he helps out. In other episodes as Kirby fights, Sir Meta Knight sometimes has no way to help out and just watches while calmly saying "Kirby."
In the start of the duel in episode 3, the impression everyone thought was Sir Meta Knight was Kirby's enemy. Sir Meta Knight claims to be King Dedede's servant, however didn't plan to defeat Kirby as he was ordered to. Throughout the duel Sir Meta Knight teaches Kirby the basics of fighting with a sword and the "sword beam" technique. Kirby falls asleep and Sir Meta Knight decides to try attack him. Just as Sir Meta Knight approaches Kirby, a rock falls off the cliff where they stood. Sir Meta Knight shouts "Watch out!" and shoves Kirby out of harms way. The rock was pushed by Fumu and Bun in attempt to save Kirby from Sir Meta Knight's attack. Later on Sir Meta Knight seemed worried about Kirby and searches for him with Sword and Blade. He thought they should find Kirby before King Dedede summons a sword-wielding demon beast. By the end of episode 3 it became clear that Sir Meta Knight's real intention was to teach Kirby how to use a sword. He used the opportunity to train Kirby.
In episode 26 when Kirby and Bun were suddenly attacked by the demon beast Chilidog, Sir Meta Knight then shows up to protect Kirby. More later on in the episode while Sir Meta Knight is fighting Chilidog he collapses from the enemy's attack. Before he fell unconscious he begs Sword and Blade to protect Kirby at all costs.
Relationship with Sword and Blade:
Sword and Blade are Sir Meta Knight's faithful companions. Sword and Blade's loyalty are so strong they would do anything to help their lord, even give their lives. How they met is explained in episode 26. Sword and Blade were in the war long ago. They became bandits to survive. One day they threat Sir Meta Knight for money. The demon beast Chilidog, which was after him attacks Sword and Blade. Sir Meta Knight saves them. After that, they swear loyalty to him. Ever since Sword and Blade sworn their loyalty to Sir Meta Knight, they followed where ever he led them. When Sir Meta Knight is not by himself, his companions are always by his side. Sword and Blade appear to get along very well with Sir Meta Knight and even watch Channel DDD with him. Sword and Blade can use a sword, but not as skillfully as Sir Meta Knight. The two seem to be good at working with mechanical and technical things, like fixing ships. They use that talent as another way to help their lord.
Relationship with Fumu:
Fumu is the daughter of Parm and Memu. Whenever Kirby gets in trouble Fumu tries her best to help him. If a time comes when Fumu can't solve the problem she usually consults to Sir Meta Knight for advice or he shows up. Fumu and Sir Meta Knight likely are the few sharp ones to notice anything strange when King Dedede orders a demon beast. They keep close eye on Kirby as much as they can and work together to stop King Dedede's stupid plots. Fumu isn't a fighter and sometimes will be in danger and unable to save herself. Sir Meta Knight tries to save her, otherwise if he can't they depend on Kirby.
Relationship with King Dedede:
Dedede is the king of Pupupu Land. Sir Meta Knight came to Popstar when his Starship detected demon beasts. The cause of this is because of the demon beast delivery system in King Dedede's throne room. King Dedede often calls Customer Service to order demon beasts from Holy Nightmare Corporation. King Dedede likes to use them to fight against Kirby. Many times King Dedede does something foolish, in which Sir Meta Knight sees him as an idiot. So is said, Sir Meta Knight knew of the demon beast delivery system and only became a servant of King Dedede thinking another Star Warrior would surely appear because of it.
Relationship with Knuckle Joe's father:
Knuckle Joe's father, also a Star Warrior fought side by side with Sir Meta Knight during the war against Nightmare. Both of them were good friends. Knuckle Joe's father was indeed a great ally to the Galaxy Soldier Army and even helped others get stronger. During a enemy attack, Knuckle Joe's father was captured and then turned into a demon beast. The next time they met, Sir Meta Knight was forced to kill him. Before Knuckle Joe's father died he gave Sir Meta Knight his pendant.
Relationship with Knuckle Joe:
Knuckle Joe is the son of Sir Meta Knight's good friend. Knuckle Joe is a skilled young fighter. He learns his father was killed by a Star Warrior and comes to Popstar to avenge him. Kirby gets mistaken for being the one who killed his father. Knuckle Joe attacks Kirby until Sir Meta Knight stops him. Sir Meta Knight explains the one who killed his father was not Kirby, but himself. After hearing the story, it became clear there was nothing else that could have been done. He decides to become allies with Sir Meta Knight and Kirby. He does prove to be a good ally in several episodes. Sometime in episode 65, Knuckle Joe was given his father's pendant that Sir Meta Knight was entrusted to. In episode 99, Knuckle Joe along with other allies help The Halberd break through a raid of enemy battleships.
Relationship with Silica:
Silica is the daughter of Garlude, her mother. Long ago, the sacred sword Galaxia was stolen by a demon beast. Sir Meta Knight and Garlude went in search for it. They were able to get the sword back, but Garlude was killed. Later, Silica's ship lands on Popstar. She was on a search for a Star Warrior, Sir Meta Knight. Silica believed her mother was betrayed by Sir Meta Knight, but comes to realize he really didn't betray her at all. Her mother had sacrificed her own life to help him get the sword. After learning the truth, Silica says goodbye and leaves Popstar. She returns in episode 99 with Knuckle Joe and Sir Arthur to help The Halberd.
Relationship with Sir Arthur:
When The Halberd was at the Nightmare fortress in episode 99, Knuckle Joe, Silica, and a group of four soldiers appear. The four are Sir Arthur, Sir Dragato, Sir Nonsurat, and Sir Falspar. Not much is said about them except they're part of the Galaxy Soldier Army. One of the Cappies in episode 52 said Sir Arthur is the Galaxy Soldier Army leader.
Relationship with Dakonyo:
Dakonyo is a soldier of the Galaxy Soldier Army that lives alone on a island. While living on the island he meets Kirby, Fumu, and Bun. He believes the war is still going on and suspects Kirby to be a demon beast. Fumu and Bun try to tell him the war ended long ago and Sir Meta Knight is currently living in Pupu Village. At first, Dakonyo doesn't believe them and eventually finds out Kirby is a Star Warrior. A fight between Kirby and a demon beast occurs on the island. Soon after Kirby wins, Dakonyo was invited to come to Pupu Village to meet Sir Meta Knight. Dakonyo declines the offer and stays on the island, but would come if anything happens. Episode 98, he comes to Pupu Village and meets Sir Meta Knight in the place where The Halberd was kept. Dakonyo salutes him while Sir Meta Knight salutes back. It appeared they knew each other. The soldier helps by joining everyone on The Halberd to Nightmare's fortress.
Relationship with Yamikage:
Yamikage is a powerful Ninja. Very little is said between Yamikage and Sir Meta Knight. During the war, ninjas were allies with the Galaxy Soldier Army. One day, the ninjas turned against the Galaxy Soldier Army and sided with Nightmare instead. The reason was not mentioned, but ever since then, ninjas have been their enemies. Sometime later on, Yamikage gets summoned by the demon beast delivery system and is sent to attack Kirby. When Yamikage recognizes Sir Meta Knight, he throws a shuriken at him and runs off. The reason why Yamikage betrayed the Galaxy Soldier Army is still unclear.