This is something I was thinking of doing last night, but I got distracted by IMMINENT internet doom. List of my characters' relationships! Just a list, mind, I have a hard enough time remembering them all without going into detail.

Mac
Perpetua - SISTER
Henry - BEST MATE
Zoe - best mate's hot older sister
Sylvia - ex girlfriend who isn't as crazy as she used to be
Sean, Paul, Louis, Josiah - roommates (closest to Paul and Sean)
Emily - fellow BEATER
Rhys - Captain
Isabelle - main current crush
Hollyoaks - BEST BOOBS
Keagan - cousin
Annie - NUNGAS OF DOOM
Rory Li - MLP mentee
Amber - current mentoring partner

Teddy
Victoire - (secret) wife
James - ...is James, I can't define their relationship really? pseudo older brother figureish?
Scorpius - COUSIN
Albus, Lily - similarly older-brotherish to James, but less
Dominique, Louis - (secret) in-laws
Nathaniel, Bartholomew - flatmates
Alex - casualish friend
Kitty - casualish friend
Peter - he considers him a protegee now

Renee
Leonard - older (mean) brother
Pascal - younger (less overtly mean) brother
Peyton - BFF, roommate
Saoirse, Brooke, Juno - ex-roomies
Jeremy - semi-secret fling, roommate
Ada - GODDESS
Lily - ...also can't quite define it
James - semi-foe

Eric
Charlotte - younger sister
Molly - best friend, ex-girlfriend, flatmate
James - former foe
Saoirse - ex-girlfriend
Danielle - ex-girlfriend
Fatima - ex-girlfriend
Asha - befuddling ex-girlfriend
Beth - childhood friend
Zoe - childhood friend grown apart?
Nick, Thomas, Ethan, Bruce - former roommates
Colin - friend, dating flatmate/bff/ex-girlfriend
Aaron - I don't know, but he feels like he should help/watch over him a little
Adam - ?

Corrie
Alexsandycarl - mostly cool older brother
Hollyoaks - bickery younger sister
Zoe - OMGWTFBFF
Lorcan - boyfriend boyfriend yay
Lysander - boyfriend's twin brother ew(ish)
Rhiannon - friend by choice!
Lourdes - friend
Scorpius - default mortal foe
Harrison - AWESOME fun guy!
Ewan - ex-boyfriend
Noah - ex-snog
Annie, Lucy, Maeve, Brooke - roommates
Luke, Josh - main guypals
Henry - BFF's spazzy little brother
Isabelle - sister's spazzy bff
James - friend or foe
Nate, Patrick - childhood friends
Imogene, Killian, Sarah, Ada, Brandon, Victor - semicousins
Anne - REAL cousin

Marietta
Cho - BFF, princess
Roger - first kiss

I may have forgotten something somewhere. I may add to this if/when I remember.