Soldier of Love
Haruka & Michiru's relationship with Minako.
Minako is the leader of the inner soldiers and although she has a habit of being obsessed with idols and can be a little flakey, she's a very reliable and dedicated sailor soldier. Initially, she believes Haruka is a man and gets a small crush on her until Haruka coldly warns them to stay away from Infinity Academy. She begins to wonder if they are enemies and outright does not trust Uranus and Neptune, especially after being attacked by them.
Eventually, their differences are put aside and they become warriors with a shared cause. Minako still harbours some vague resentment towards Haruka and Michiru in the form of jealousy during the Dream arc, when her fellow inner soldiers keep talking about them. She feels that her group's fondness toward Haruka and Michiru means that they don't consider her to be a good enough leader… but this is of course not true and Minako is able to get past these feelings of envy.
Minako is a fan of Michiru's musical talents and is impressed with her knowledge of the Three Lights (even more so when Michiru tells her they have a joint concert together). She also shares a special leadership bond with Haruka, who is leader of the outer soldiers.
Soldier of Fire
Haruka & Michiru's relationship with Rei.
Rei is a miko who works at her grandfather's Hikawa shrine. She generally despises men and is a very independant girl with strong spiritual powers and insight. As Sailor Mars, she not only controls the power of fire, but also uses her Shinto abilities to ward off evil and break illusions. In this sense, she is very much like Sailor Neptune, who also has very strong spiritual insight. It is this insight that gave Rei a prophetic dream about the talismans and the end of the world.
Initially, Rei is very concerned about Uranus and Neptune's role in the foretold apocalypse, asking them for more information. She's worried at first that Uranus and Neptune may be the ones to bring ruin to the world; a fear strengthened once she sees they are in possession of two talismans. However, this proves to be untrue and after they become a team, Rei looks to both women as sources of strength.
Michiru is the woman that Rei thinks about when she's under attack by the Dead Moon Circus. She feels Michiru telling her that Rei's spiritual insight and nerves of steel make her outshine everyone. Thinking about Michiru gives Rei encouragement to overcome her enemy.
Soldier of Thunder
Haruka & Michiru's relationship with Makoto.
Makoto is the "brawn" of the inner soldiers. She comes off as being somewhat masculine due to her strength and height, but she's very feminine when it comes to her passion for cooking and gardening. Along with Minako, Makoto mistakes Haruka for a man and gets a small crush on her too. Her crush doesn't last long after Haruka acts coldly towards her and the other girls.
Also like Minako, Makoto doesn't trust Uranus and Neptune and is very vocal in her mistrust towards them but she eventually grows to appreciate and look up to both Haruka and Michiru. Makoto thinks Michiru is beautiful and elegant and hopes to be more like her in those aspects while she wishes she was stronger like Haruka.
When Makoto faces the Dead Moon Circus, she thinks to Haruka as a source of encouragement. Both Makoto and Haruka are powerful women with very strong, protective natures. Haruka sends her a message saying "The enemy that is even greater than the one you fight is your own weakness" and this gives Makoto enough motivation to stand up and fight for those she wants to protect.
Soldier of Water
Haruka & Michiru's relationship with Ami.
The studious and intellectual Ami is the "brains" of the inner soldiers. She is a little shy and a bit reserved but she's both resourceful and determined and provides important strategy and reconnaissance to her group. Ami finds herself relating to Setsuna more than Haruka or Michiru, but she looks up to all three of them as being powerful allies. She also mentions that she really likes Michiru's violin music.
When Ami infiltrates Infinity Academy, she gets in over her head when she's targeted by Viluy. Haruka and Michiru see her running past and decide to follow her. Even at the risk of blowing their cover, the two can't stand by and let the enemy attack Ami so they transform and protect her. Later, Ami looks up to the outers, just as Rei and Makoto do.
As one of the "stars" of Juuban High School, Ami seems to share Haruka and Michiru's opinions regarding the Three Lights and the three of them are visually flustered when the other girls praise them. Like Haruka, Ami definitely doesn't like to be shown up in her specialties.