Russell and Lori are very important.
To Rin, who’s lost his father and become distant to his maternal family; there’s nothing more heartwarming than coming back to a country he lived in for a short while and being greeted with open arms.
Russell and Lori treat Rin like their own son and they treat Haru with the same casual, loving and friendly atmosphere.
What Rin needed the most in his hard, insecure and lonely days in Australia was family and friendship. Lori and Russell instinctively knew that something was wrong with Rin and worried and fussed over him as any other family would do. Despite the hardships of Rin’s limited English.
He wasn’t treat like some kid who turned up from Japan to swim.
These two wonderful parents are even treating Haru like a beloved family member, asking him how he is and about his life because they know just how important Haru is to Rin. Lori even makes sure to cook food that Haru is familiar with so he doesn’t feel as uncomfortable in this new foreign place.
Haru has probably never experienced this sort of behavior coming from anyone but the Tachibana family so I think that with Haru being exposed to a family atmosphere is a really crucial part of his development and also, to his happiness. Haruka was in denial of his friendships and about where he stood in the world, with his introduction to Lori and Russell he’s reminded of the close bonds and ties he has to his own friends and family. This is the reason why he’s pulled out of his slump.
TLDR: This is basically just an appreciation post for Rin’s amazing Australian host family.