There are several ways to help an audience connect with the relationships between two or more characters. (In)Famously, there is the meet cute, wherein two people meet in a contrived, coincidental, but “cute” way, like bumping heads when reaching for the same dropped book or something. There are also “frenemies,” who begin as diametrically enemies and slowly become friends, investing the audience in their transformation, like Crowley and the Winchesters on SUPERNATURAL. And there are always the diverse group of people thrown together, like the study group on COMMUNITY or Leia, Luke, and Hanh in STAR WARS.
With the right dynamics, these are all legitimate ways to invest an audience in a set of relationships. However, I think one of the most effective ways of connecting an audience with two characters is to pair contrasts together. The Amazon Prime show TRUTH SEEKERS relies on this dynamic for several of its characters to great effect.
TRUTH SEEKERS makes the audience care about the relationships between its characters by making them odd pairs of contrasts who have a singular thing in common. The two core pairs in the show lean on this with the relationships between Gus (a middle-aged widower who is interested in the paranormal) and Elton (a single wanderer that attracts the paranormal), and Richard (a lonely old man) and Helen (an agoraphobic young woman).
For Gus and Elton, they both have the paranormal in common. Gus is attracted to it, mostly because of his late wife, while Elton is repelled from it due to an experience when he was a child. Unfortunately for Elton, but to Gus’s delight, the paranormal is attracted to him. This automatically introduces conflict into their relationship, so the audience is immediately invested in seeing them work together and come to an understanding.
Richard and Helen have loneliness in common. Only in Richard’s case it’s because he’s old and stuck in his house all day, while Helen is young but afraid to leave her house. The audience roots for them to solve one another’s loneliness and for Richard to help Helen overcome her agoraphobia.
These types of dynamics are shortcuts for the audience to identify with and latch onto characters. TRUTH SEEKERS does it especially well, in my opinion, because of the commonalities between the characters and how that allows them to help one another grow.